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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Information Required in Proxy Statement
Schedule 14A Information
Proxy Statement Pursuant to Section 14(a)
of the Securities Exchange Act of 1934

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Filed by a Party other than the Registrant ☐

Check the appropriate box:

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Preliminary Proxy Statement

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Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

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Definitive Proxy Statement

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Definitive Additional Materials

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Soliciting Material Pursuant to §240.14a-12

ALTC ACQUISITION CORP.

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

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No fee required.

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Fee paid previously with preliminary materials.

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Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11.

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ALTC ACQUISITION CORP.
640 FIFTH AVENUE, 12TH FLOOR
NEW YORK, NY 10019

Dear AltC Acquisition Corp. Stockholder:

You are cordially invited to attend a special meeting of stockholders of AltC Acquisition Corp., a Delaware corporation (“AltC” or the “Company”), which will be held on October 5, 2023, at 11:00 a.m., Eastern Time (the “Special Meeting”).

The Special Meeting will be held virtually. You may attend the Special Meeting and vote your shares electronically during the Special Meeting via live webcast by visiting https://www.cstproxy.com/altcacquisitioncorp/2023. You will need the 12-digit meeting control number that is printed on your proxy card to enter the Special Meeting. AltC recommends that you log in at least 15 minutes before the Special Meeting to ensure you are logged in when the Special Meeting starts. Please note that you will not be able to attend the Special Meeting in person.

As more fully described in the accompanying proxy statement, the purpose of the Special Meeting is to consider and vote upon the following proposals:

Proposal No. 1 — The “Extension Amendment Proposal” — To amend AltC’s amended and restated certificate of incorporation (the “Certificate of Incorporation”), in the form set forth in Annex A to the accompanying proxy statement, which we refer to as the “Extension Amendment” and, such proposal, the “Extension Amendment Proposal”, to extend the date by which AltC must consummate a merger, capital stock exchange, asset acquisition, stock purchase, reorganization or similar business combination with one or more businesses, which we refer to as a “business combination”, from October 12, 2023 (the “Termination Date”), to July 12, 2024 (or such earlier date as determined by AltC’s board of directors (the “Board”)), which we refer to as the “Extension,” and such later date the “Extended Date.”

Proposal No. 2 — The “Adjournment Proposal” — To adjourn the Special Meeting to a later date or dates, if necessary, to permit further solicitation and vote of proxies if, at the time of the Special Meeting, there are not sufficient votes to approve the Extension Amendment Proposal or if AltC determines that additional time is necessary to effectuate the Extension (the “Adjournment Proposal”).

The Adjournment Proposal will only be presented at the Special Meeting if, based on the tabulated votes, there are not sufficient votes at the time of the Special Meeting to approve the Extension Amendment Proposal or if AltC determines that additional time is necessary to effectuate the Extension, in which case the Adjournment Proposal will be the only proposal presented at the Special Meeting.

Each of the Extension Amendment Proposal and the Adjournment Proposal are more fully described in the accompanying proxy statement. Please take the time to read carefully each of the proposals in the accompanying proxy statement before you vote.

As previously disclosed, on July 11, 2023, AltC, AltC Merger Sub, Inc., a Delaware corporation and a direct, wholly-owned subsidiary of AltC (“Merger Sub”), and Oklo Inc., a Delaware corporation (“Oklo”), entered into that certain Agreement and Plan of Merger and Reorganization (as it may be amended from time to time, the “Merger Agreement”), pursuant to which, among other things, Merger Sub will merge with and into Oklo, with Oklo surviving such merger as a wholly-owned subsidiary of AltC (the “Merger”). We refer to the Merger and the other transactions described in the Merger Agreement as the “Business Combination.” For more information about the Business Combination, see our Current Report on Form 8-K filed with the SEC on July 11, 2023. No assurances can be made that AltC will successfully consummate a Business Combination.

The purpose of the Extension Amendment Proposal and, if necessary, the Adjournment Proposal, is to allow AltC additional time to complete the Business Combination.

The Certificate of Incorporation provides that AltC currently has until the Termination Date to complete its initial business combination. The Board unanimously (of those who voted) has determined

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that it is in the best interests of AltC to seek an extension of the Termination Date and ask AltC’s stockholders to approve the Extension Amendment Proposal to allow for additional time to complete the Business Combination. AltC will call a separate special meeting of its stockholders to approve the Business Combination (referred to herein as the “Business Combination Special Meeting”). The Board believes that it is in the best interests of AltC stockholders that the Extension be implemented so that AltC will have additional time to complete the Business Combination.

Without the Extension, AltC would not be able to complete the Business Combination on or before the Termination Date. If that were to occur, AltC would be forced to liquidate even if AltC’s stockholders are otherwise in favor of consummating the Business Combination. If the Extension Amendment Proposal is not approved and the Business Combination is not completed on or before the Termination Date, AltC will: (i) cease all operations except for the purpose of winding up, (ii) as promptly as reasonably possible but not more than ten business days thereafter subject to lawfully available funds therefor, redeem 100% of the outstanding shares of Class A common stock, par value $0.0001 per share (the “Class A Common Stock”), that were sold in AltC’s initial public offering, which was consummated on July 12, 2021 (the “Public Shares”), in consideration of a per share price, payable in cash, equal to the quotient obtained by dividing (A) the aggregate amount then on deposit in AltC’s U.S. based trust account maintained by Continental Stock Transfer & Trust Company, acting as trustee (the “Trust Account”), including interest (net of amounts withdrawn to fund AltC’s working capital requirements, subject to an annual limit of $1,000,000 (but, notwithstanding the annual limitation, such withdrawals can only be made from interest and not from the principal held in the Trust Account), and to pay its tax obligations (“Permitted Withdrawals”) and less up to $100,000 of such net interest to pay dissolution expenses), by (B) the total number of then outstanding Public Shares, which redemption will completely extinguish rights of the public stockholders (including the right to receive further liquidating distributions, if any), subject to applicable law, and (iii) as promptly as reasonably possible following such redemption, subject to the approval of the remaining stockholders and the Board in accordance with applicable law, dissolve and liquidate, subject in each case to AltC’s obligations under the Delaware General Corporation Law (the “DGCL”) to provide for claims of creditors and other requirements of applicable law.

If the Extension is approved and implemented, subject to satisfaction of the conditions to closing in the Merger Agreement (including, without limitation, receipt of the approval of the stockholders of AltC at the Business Combination Special Meeting), AltC intends to complete the Business Combination as soon as practicable and in any event on or before the Extended Date. No assurances can be made that AltC will consummate a Business Combination.

As contemplated by the Certificate of Incorporation, the holders of Public Shares may elect to redeem all or a portion of their Public Shares in exchange for their pro rata portion of the funds held in the Trust Account if the Extension is implemented (the “Redemption”). If AltC does not implement the Extension, it will not redeem any Public Shares submitted for Redemption in connection with the Special Meeting.

On the Record Date (as defined below), the redemption price per share was approximately $10.33, based on the aggregate amount on deposit in the Trust Account of approximately $516,729,800 as of the Record Date (including interest not previously released to AltC but net of taxes payable), divided by the total number of then outstanding Public Shares. The closing price of shares of the Class A Common Stock on the New York Stock Exchange on the Record Date was $10.34 per share. Accordingly, if the market price of shares of the Class A Common Stock were to remain the same until the date of the Special Meeting, exercising redemption rights would result in a public stockholder receiving approximately $0.01 less per share than if the stock was sold in the open market. AltC cannot assure stockholders that they will be able to sell their Public Shares in the open market, even if the market price per share is higher than the redemption price stated above, as there may not be sufficient liquidity in its securities when such stockholders wish to sell their shares. AltC believes that such redemption right enables its public stockholders to determine whether or not to sustain their investments for an additional period if AltC does not complete the Business Combination on or before the Termination Date.

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Notwithstanding stockholder approval of the Extension Amendment Proposal, the Board will retain the right to abandon and not implement the Extension Amendment at any time without any further action by our stockholders. AltC will not proceed with the Extension if the number of redemptions of our Public Shares (after taking into account any Election Reversals (as defined below)) causes AltC to have less than $5,000,001 of net tangible assets following approval of the Extension Amendment Proposal. The Merger Agreement provides that the consummation of the Business Combination is conditioned upon, among other things, AltC having at least $5,000,001 of net tangible assets as of the closing of the Business Combination. Additionally, the obligations of Oklo to consummate the Business Combination are conditioned upon, among other things, the amount of cash available in the Trust Account (including, the net proceeds of any incremental financing raised by AltC or Oklo in connection with the transactions contemplated by the Merger Agreement) being at least $250,000,000, after reduction for redemptions made in connection with the Business Combination Special Meeting and any excise tax payable by AltC, but before giving effect to the payment of transaction expenses.

The accompanying proxy statement provides stockholders with detailed information about the Extension Amendment Proposal and other matters to be considered at the Special Meeting, including AltC stockholders’ right to redeem their Public Shares for a pro rata portion of the cash held in the Trust Account in connection with the Extension. We encourage you to read the entire accompanying proxy statement, including any Annexes and other documents referred to therein, carefully and in their entirety.

TO EXERCISE YOUR REDEMPTION RIGHTS, YOU MUST ELECT TO HAVE ALTC REDEEM YOUR SHARES FOR A PRO RATA PORTION OF THE FUNDS HELD IN THE TRUST ACCOUNT AND TENDER YOUR SHARES TO ALTC’S TRANSFER AGENT (EACH, AN “ELECTION” AND COLLECTIVELY, THE “ELECTION”) PRIOR TO 5:00 P.M. EASTERN TIME ON OCTOBER 3, 2023 (TWO BUSINESS DAYS PRIOR TO THE VOTE AT THE SPECIAL MEETING) (THE “REDEMPTION DEADLINE”). YOU MAY TENDER YOUR SHARES BY EITHER DELIVERING YOUR SHARE CERTIFICATE TO THE TRANSFER AGENT OR BY DELIVERING YOUR SHARES ELECTRONICALLY USING THE DEPOSITORY TRUST COMPANY’S DWAC (DEPOSIT WITHDRAWAL AT CUSTODIAN) SYSTEM. IF THE EXTENSION IS NOT APPROVED, THEN THESE SHARES WILL NOT BE REDEEMED FOR CASH. IF YOU HOLD THE SHARES IN STREET NAME, YOU WILL NEED TO INSTRUCT THE ACCOUNT EXECUTIVE AT YOUR BANK OR BROKER TO WITHDRAW THE SHARES FROM YOUR ACCOUNT IN ORDER TO EXERCISE YOUR REDEMPTION RIGHTS.

Immediately following the Redemption Deadline, a public stockholder that makes an Election may withdraw its Election with respect to all or a portion of its Public Shares for which it previously submitted an Election (an “Election Reversal”). See “The Extension Amendment Proposal — Redemption Withdrawal Procedures.”

TO MAKE AN ELECTION REVERSAL WITH RESPECT TO YOUR PUBLIC SHARES, YOU MUST SUBMIT A WRITTEN REQUEST TO THE TRANSFER AGENT, AFTER 5:00 P.M. EASTERN TIME ON OCTOBER 3, 2023, THE DATE THAT IS TWO BUSINESS DAYS PRIOR TO THE SCHEDULED VOTE AT THE SPECIAL MEETING, AND PRIOR TO THE SCHEDULED VOTE AT THE SPECIAL MEETING, THAT THE ELECTION TO REDEEM YOUR PUBLIC SHARES BE REVERSED, INCLUDING THE LEGAL NAME, PHONE NUMBER, AND ADDRESS OF THE BENEFICIAL OWNER OF THE SHARES FOR WHICH REVERSAL IS REQUESTED AND THE NUMBER OR PERCENTAGE OF SHARES FOR WHICH REVERSAL IS REQUESTED. IF YOU HOLD THE SHARES IN STREET NAME, YOU WILL NEED TO INSTRUCT THE ACCOUNT EXECUTIVE AT YOUR BANK OR BROKER TO REQUEST REVERSAL OF THE ELECTION TO REDEEM FROM THE TRANSFER AGENT.

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The Board has fixed the close of business on September 1, 2023 (the “Record Date”), as the date for determining AltC’s stockholders entitled to receive notice of and vote at the Special Meeting and any adjournment thereof. Only holders of record of Common Stock on that date are entitled to have their votes counted at the Special Meeting or any adjournment thereof.

You are not being asked to vote on the Business Combination at this time. If the Extension is implemented and you do not elect to redeem your Public Shares, provided that you are a stockholder on the record date for the Business Combination Special Meeting, you will retain the right to vote on the Business Combination when it is submitted to AltC’s stockholders and the right to redeem your Public Shares for cash in the event the Business Combination is approved and completed or we have not consummated a business combination by the Extended Date.

After careful consideration of all relevant factors, the Board unanimously (of those who voted) has determined that the Extension Amendment Proposal and, if presented, the Adjournment Proposal are in the best interests of AltC and its stockholders, has declared it advisable and recommends that you vote or give instruction to vote “FOR” such proposals.

Enclosed is the proxy statement containing detailed information about the Special Meeting, the Extension Amendment Proposal and the Adjournment Proposal. Whether or not you plan to attend the Special Meeting, AltC urges you to read this material carefully and vote your shares.

By Order of the Board of Directors of AltC Acquisition Corp.

/s/ Michael Klein

Michael Klein
Chairman of the Board of Directors
September 14, 2023

The accompanying proxy statement is dated September 14, 2023, and is first being mailed to stockholders of the Company on or about that date.

IMPORTANT

Your vote is very important. Whether or not you plan to attend the Special Meeting online, please vote as soon as possible by following the instructions in the accompanying proxy statement to make sure that your shares are represented at the Special Meeting. If you hold your shares in “street name” through a bank, broker or other nominee, you will need to follow the instructions provided to you by your bank, broker or other nominee to ensure that your shares are represented and voted at the Special Meeting.

Important Notice Regarding the Availability of Proxy Materials for the Special Meeting of Stockholders to be held on October 5, 2023: This notice of meeting and the accompanying proxy statement are available at https://www.cstproxy.com/altcacquisitioncorp/2023.

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NOTICE OF SPECIAL MEETING OF STOCKHOLDERS
OF ALTC ACQUISITION CORP.
TO BE HELD ON OCTOBER 5, 2023

To the Stockholders of AltC Acquisition Corp.:

NOTICE IS HEREBY GIVEN that a special meeting of stockholders (the “Special Meeting”) of AltC Acquisition Corp., a Delaware corporation (“AltC,” “we,” “our” or “us”), will be held on October 5, 2023, at 11 a.m., Eastern Time, via live webcast at the following address: https://www.cstproxy.com/altcacquisitioncorp/2023. You will need the 12-digit meeting control number that is printed on your proxy card to enter the Special Meeting. AltC recommends that you log in at least 15 minutes before the Special Meeting to ensure you are logged in when the Special Meeting starts. Please note that you will not be able to attend the Special Meeting in person. You are cordially invited to attend the Special Meeting for the following purposes:

Proposal No. 1 — The “Extension Amendment Proposal” — To amend AltC’s amended and restated certificate of incorporation (the “Certificate of Incorporation”), in the form set forth in Annex A to this proxy statement, which we refer to as the “Extension Amendment” and, such proposal, the “Extension Amendment Proposal”, to extend the date by which AltC must consummate a merger, capital stock exchange, asset acquisition, stock purchase, reorganization or similar business combination with one or more businesses, which we refer to as a “business combination” from October 12, 2023 (the “Termination Date”), to July 12, 2024 (or such earlier date as determined by the board of directors of AltC (the “Board”)), which we refer to as the “Extension” and, such later date, the “Extended Date”;

As previously disclosed, on July 11, 2023, AltC, AltC Merger Sub, Inc., a Delaware corporation and a direct, wholly-owned subsidiary of AltC (“Merger Sub”), and Oklo Inc., a Delaware corporation (“Oklo”), entered into that certain Agreement and Plan of Merger and Reorganization (as it may be amended form time to time, the “Merger Agreement”), pursuant to which, among other things, Merger Sub will merge with and into Oklo, with Oklo surviving such merger as a wholly-owned subsidiary of AltC (the “Merger”). We refer to the Merger and the other transactions described in the Merger Agreement as the “Business Combination.” For more information about the Business Combination, see our Current Report on Form 8-K filed with the SEC on July 11, 2023.

The purpose of the Extension Amendment Proposal and, if necessary, the Adjournment Proposal, is to allow AltC additional time to complete the Business Combination.

The Certificate of Incorporation provides that AltC currently has until the Termination Date to complete its initial business combination. The Board unanimously (of those who voted) has determined that it is in the best interests of AltC to seek an extension of the Termination Date and ask AltC’s stockholders approve the Extension Amendment Proposal to allow for additional time to complete the Business Combination. AltC will call a separate special meeting of its stockholders to approve the Business Combination (referred to herein as the “Business Combination Special Meeting”). The Board believes that it is in the best interests of AltC stockholders that the Extension be implemented so that AltC will have additional time to complete the Business Combination.

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that were sold in AltC’s initial public offering, which was consummated on July 12, 2021 (“initial public offering” or “IPO” and, such shares sold in the IPO, the “Public Shares”), in consideration of a per share price, payable in cash, equal to the quotient obtained by dividing (A) the aggregate amount then on deposit in AltC’s U.S. based trust account maintained by Continental Stock Transfer & Trust Company, acting as trustee (the “Trust Account”), including interest (net of amounts withdrawn to fund AltC’s working capital requirements, subject to an annual limit of $1,000,000 (but, notwithstanding the annual limitation, such withdrawals can only be made from interest and not from the principal held in the Trust Account), and to pay its tax obligations (“Permitted Withdrawals”) and less up to $100,000 of such net interest to pay dissolution expenses), by (B) the total number of then outstanding Public Shares, which redemption will completely extinguish rights of the public stockholders (including the right to receive further liquidating distributions, if any), subject to applicable law, and (iii) as promptly as reasonably possible following such redemption, subject to the approval of the remaining stockholders and the Board in accordance with applicable law, dissolve and liquidate, subject in each case to AltC’s obligations under the Delaware General Corporation Law (the “DGCL”) to provide for claims of creditors and other requirements of applicable law.

As contemplated by the Certificate of Incorporation, the holders of Public Shares may elect to redeem all or a portion of their Public Shares in exchange for their pro rata portion of the funds held in the Trust Account if the Extension is implemented (the “Redemption”). If AltC does not implement the Extension, it will not redeem any Public Shares submitted for the Redemption in connection with the Special Meeting.

On the Record Date (as defined below), the redemption price per share was approximately $10.33, based on the aggregate amount on deposit in the Trust Account of approximately $516,729,800 as of the Record Date (including interest not previously released to AltC but net of taxes payable), divided by the total number of then outstanding Public Shares. The closing price of the shares of Class A Common Stock on the New York Stock Exchange on the Record Date was $10.34 per share. Accordingly, if the market price of shares of the Class A Common Stock were to remain the same until the date of the Special Meeting, exercising redemption rights would result in a public stockholder receiving approximately $0.01 less per share than if the stock was sold in the open market. AltC cannot assure stockholders that they will be able to sell their Public Shares in the open market, even if the market price per share is higher than the redemption price stated above, as there may not be sufficient liquidity in its securities when such stockholders wish to sell their shares. AltC believes that such redemption right enables its public stockholders to determine whether or not to sustain their investments for an additional period if AltC does not complete the Business Combination on or before the Termination Date.

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Approval of the Extension Amendment Proposal requires the affirmative vote of the holders, as of the Record Date, of at least 65% of all outstanding shares of Class A Common Stock and Class B Common Stock, par value $0.0001 per share, of the Company (the “Class B Common Stock” or “founder shares” and, together with the Class A Common Stock, the “Common Stock”), voting together as a single class. Notwithstanding stockholder approval of the Extension Amendment Proposal, the Board will retain the right to abandon and not implement the Extension Amendment at any time without any further action by our stockholders. AltC will not proceed with the Extension if the number of redemptions of our Public Shares (after taking into account any Election Reversals (as defined below)) causes AltC to have less than $5,000,001 of net tangible assets following approval of the Extension Amendment Proposal. The Merger Agreement provides that the consummation of the Business Combination is conditioned upon, among other things, AltC having at least $5,000,001 of net tangible assets as of the closing of the Business Combination. Additionally, the obligations of Oklo to consummate the Business Combination are conditioned upon, among other things, the amount of cash available in the Trust Account (including, the net proceeds of any incremental financing raised by AltC or Oklo in connection with the transactions contemplated by the Merger Agreement) being at least $250,000,000, after reduction for redemptions made in connection with the Business Combination Special Meeting and any excise tax payable by AltC, but before giving effect to the payment of transaction expenses.

Record holders of Common Stock at the close of business on September 1, 2023 (the “Record Date”), are entitled to vote or have their votes cast at the Special Meeting. On the Record Date, there were 63,950,000 issued and outstanding shares of Common Stock.

This proxy statement (this “Proxy Statement”) contains important information about the Special Meeting, the Extension Amendment Proposal and the Adjournment Proposal. Whether or not you plan to attend the Special Meeting, AltC urges you to read this material carefully and vote your shares.

This Proxy Statement is dated September 14, 2023, and is first being mailed to stockholders on or about that date.

By Order of the Board of Directors of AltC Acquisition Corp.

/s/ Michael Klein

Michael Klein
Chairman of the Board of Directors

IMPORTANT NOTICE REGARDING THE AVAILABILITY OF PROXY MATERIALS FOR THE
SPECIAL MEETING TO BE HELD ON OCTOBER 5, 2023

This Notice of Special Meeting and this Proxy Statement are available at https://www.cstproxy.com/altcacquisitioncorp/2023.

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	CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS					ii
	RISK FACTORS					1
	QUESTIONS AND ANSWERS ABOUT THE SPECIAL MEETING					6
	BACKGROUND					17
	The Proposed Business Combination					17
	SPECIAL MEETING OF ALTC STOCKHOLDERS					18
	The AltC Special Meeting					18
	Date, Time and Place of Special Meeting					18
	Proposals at the Special Meeting					18
	Voting Power; Record Date					18
	Recommendation of the Board					19
	Quorum and Required Vote for Proposals for the Special Meeting					19
	No Additional Matters					19
	Who Can Answer Your Questions about Voting					19
	Redemption Rights					19
	Appraisal or Dissenters’ Rights					23
	Solicitation of Proxies					23
	Interests of Sponsor and AltC’s Directors and Officers					23
	PROPOSAL NO. 1 — THE EXTENSION AMENDMENT PROPOSAL					26
	Overview					26
	Reasons for the Extension Amendment Proposal					26
	If the Extension Amendment Proposal is Not Approved					27
	If the Extension Amendment Proposal is Approved					28
	Certain Material U.S. Federal Income Tax Consequences					28
	Vote Required for Approval					33
	Recommendation of the Board					34
	PROPOSAL NO. 2 — THE ADJOURNMENT PROPOSAL					35
	Overview					35
	Consequences if the Adjournment Proposal is Not Approved					35
	Vote Required for Approval					35
	Recommendation of the Board					35
	BENEFICIAL OWNERSHIP OF SECURITIES					36
	FUTURE STOCKHOLDER PROPOSALS					38
	HOUSEHOLDING INFORMATION					38
	WHERE YOU CAN FIND MORE INFORMATION					39
	ANNEX A					A-1

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CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

Certain statements in this proxy statement may constitute “forward-looking statements” within the meaning of the “safe harbor” provisions of the United States Private Securities Litigation Reform Act of 1995. Forward-looking statements may be identified by the use of words such as “estimate,” “plan,” “project,” “forecast,” “intend,” “will,” “expect,” “anticipate,” “believe,” “seek,” “target,” “continue,” “could,” “may,” “might,” “possible,” “potential,” “predict” or other similar expressions that predict or indicate future events or trends or that are not statements of historical matters. We have based these forward-looking statements on our current expectations and projections about future events. These forward-looking statements include, but are not limited to, statements regarding:

•

AltC’s ability to complete the Business Combination;

•

the anticipated benefits of the Business Combination;

•

the volatility of the market price and liquidity of the shares of Class A Common Stock and other securities of AltC;

•

the use of funds not held in the Trust Account or available to AltC from interest income on the Trust Account balance; and

•

the competitive environment in which the Oklo will operate following the Business Combination.

These statements are based on various assumptions, whether or not identified in this proxy statement, and on the current expectations of Oklo’s and AltC’s management and are not predictions of actual performance. These forward-looking statements are provided for illustrative purposes only and are not intended to serve as and must not be relied on by any investor as, a guarantee, an assurance, a prediction or a definitive statement of fact or probability. Actual events and circumstances are difficult or impossible to predict and will differ from assumptions. Many actual events and circumstances are beyond the control of Oklo and AltC. These forward-looking statements are subject to known and unknown risks, uncertainties and assumptions about us that may cause our actual results, levels of activity, performance or achievements to be materially different from any future results, levels of activity, performance or achievements expressed or implied by such forward-looking statements. Such risks and uncertainties include changes in domestic and foreign business, market, financial, political and legal conditions; the inability of the parties to successfully or timely consummate the Business Combination, including the risk that any required regulatory approvals are not obtained, are delayed or are subject to unanticipated conditions that could adversely affect the combined company or the expected benefits of the Business Combination or that the approval of the shareholders of AltC or Oklo is not obtained; the outcome of any legal proceedings that may be instituted against Oklo’s or AltC following announcement of the Business Combination; failure to realize the anticipated benefits of the Business Combination; risks relating to the uncertainty of the projected financial information with respect to Oklo; the effects of competition; changes in applicable laws or regulations; the ability of the combined company to manage expenses and recruit and retain key employees; the ability of AltC or the combined company to issue equity or equity-linked securities in connection with the Business Combination or in the future; the outcome of any potential litigation, government and regulatory proceedings, investigations and inquiries; the impact of the global COVID-19 pandemic on Oklo, AltC, the combined company’s projected results of operations, financial performance or other financial metrics, or on any of the foregoing risks; and those factors discussed in AltC’s Quarterly Reports filed by AltC with the SEC on Form 10-Q and the Annual Reports filed by AltC with the SEC on Form 10-K, in each case, under the heading “Risk Factors,” and other documents filed, or to be filed, with the SEC by AltC. If any of these risks materialize or our assumptions prove incorrect, actual results could differ materially from the results implied by these forward-looking statements. There may be additional risks which neither Oklo nor AltC presently know or which Oklo and AltC currently believe are immaterial that could also cause actual results to differ from those contained in the forward-looking statements. In addition, forward-looking statements reflect Oklo’s and AltC’s expectations, plans or forecasts of future events and views as of the date of this proxy statement. Oklo and AltC anticipate that subsequent events and developments will cause Oklo’s and AltC’s assessments to change. However, while Oklo and AltC may elect to update these forward-looking statements at some point in the future, Oklo and AltC specifically disclaim any obligation to do so. These forward-looking statements should not be relied upon as representing Oklo’s and AltC’s assessments as of any date subsequent to the date of this proxy statement. Accordingly, undue reliance should not be placed upon the forward-looking

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statements. An investment in AltC is not an investment in any of our founders’ or sponsors’ past investments or companies or any funds affiliated with any of the foregoing. The historical results of these investments are not indicative of future performance of AltC, which may differ materially from the performance of the founders or sponsors past investments, companies or affiliated funds.

iii

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RISK FACTORS

You should consider carefully all of the risks described in our Annual Report on Form 10-K filed with the SEC on March 31, 2023, our Quarterly Reports on Form 10-Q filed with the SEC on May 15, 2023, and in the other reports we may file with the SEC before making a decision on how to vote on the proposals at the Special Meeting. Furthermore, if any of the following events occur, our business, financial condition and operating results may be materially adversely affected, or we could face liquidation. In that event, the trading price of our securities could decline, and you could lose all or part of your investment. The risks and uncertainties described in the aforementioned filings and below are not the only ones we face. Additional risks and uncertainties that we are unaware of, or that we currently believe are not material, may also become important factors that adversely affect our business, financial condition and operating results or result in our liquidation.

There are no assurances that the Extension will enable us to complete a business combination.

Approving the Extension involves a number of risks. Even if the Extension is approved, the Company can provide no assurances that an initial business combination will be consummated prior to the Extended Date (as defined below). Our ability to consummate any business combination is dependent on a variety of factors, many of which are beyond our control. If the Extension is approved, the Company expects to seek stockholder approval of the Business Combination by means of a proxy statement/prospectus that will be filed with the U.S. Securities and Exchange Commission (the “SEC”) following the SEC declaring effective a Registration Statement on Form S-4 (the “Business Combination Registration Statement”) relating to the stockholder meeting to approve the Business Combination. The Business Combination Registration Statement has not been filed with or declared effective by the SEC, and the Company cannot complete the Business Combination unless the Business Combination Registration Statement is declared effective by the SEC. As of the date of this Proxy Statement, the Company cannot estimate when, or if, the SEC will declare the Business Combination Registration Statement effective.

We are required to offer stockholders the opportunity to redeem shares in connection with the Extension Amendment, and we will be required to offer stockholders redemption rights again in connection with any stockholder vote to approve the Business Combination. We may experience high levels of redemptions in connection with the Extension Amendment or in connection with any stockholder vote to approve the Business Combination. Even if the Extension or the Business Combination are approved by our stockholders, it is possible that redemptions will leave us with insufficient cash to consummate the Business Combination on commercially acceptable terms, or at all.

The fact that we will have separate redemption periods in connection with the Extension and the Business Combination vote could exacerbate these risks. Other than in connection with a redemption offer or liquidation, our stockholders may be unable to recover their investment except through sales of our shares on the open market. The price of our shares may be volatile, and there can be no assurance that stockholders will be able to dispose of our shares at favorable prices, or at all.

Regulatory delays could cause us to be unable to consummate the Business Combination.

We are not aware of any material regulatory approvals or actions that are required for completion of the Business Combination other than the SEC’s review of the Business Combination Registration Statement and the expiration or early termination of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended. It is presently contemplated that if any additional regulatory approvals or actions are required, those approvals or actions will be sought. There can be no assurance, however, that any additional approvals or actions will be obtained on a timely basis, or at all. This includes any potential review by a U.S. government entity, such as the Committee on Foreign Investment in the United States (“CFIUS”), on account of certain foreign ownership restrictions on U.S. businesses. We do not believe that either we or our sponsor, AltC Sponsor LLC (“Sponsor”), constitute, are controlled by or have substantial ties with, a “foreign person” under CFIUS rules and regulations. However, if CFIUS considers us to be a “foreign person”, we could be subject to such foreign ownership restrictions and/or CFIUS review.

Because we have only a limited time to complete our initial business combination, even if we are able to effect the Extension, our failure to obtain any required regulatory approvals in connection with the Business

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Combination may require us to liquidate. If we liquidate, our public stockholders may only receive an amount per share based on the funds available in our Trust Account. This will also cause you to lose any potential investment opportunity in a target company and the chance of realizing future gains on your investment through any price appreciation in the combined company.

We may be subject to a new 1% U.S. federal excise tax in connection with redemptions of our shares of Class A Common Stock.

On August 16, 2022, the Inflation Reduction Act of 2022 (the “IR Act”) was signed into law. The IR Act provides for, among other things, a new 1% U.S. federal excise tax on certain repurchases (including redemptions) of stock by publicly traded U.S. corporations after December 31, 2022. The excise tax is imposed on the repurchasing corporation itself, not its stockholders from whom the shares are repurchased (although it may reduce the amount of cash distributable in a current or subsequent redemption). The amount of the excise tax is generally 1% of any positive difference between the fair market value of any shares repurchased by the repurchasing corporation during a taxable year and the fair market value of certain new stock issuances by the repurchasing corporation during the same taxable year. In addition, a number of exceptions apply to this excise tax. The U.S. Department of the Treasury (the “Treasury”) has been given authority to provide regulations and other guidance to carry out, and prevent the abuse or avoidance of, this excise tax.

On December 27, 2022, the Treasury published Notice 2023-2, which provided clarification on some aspects of the application of the excise tax. The notice generally provides that if a publicly traded U.S. corporation completely liquidates and dissolves, distributions in such complete liquidation and other distributions by such corporation in the same taxable year in which the final distribution in complete liquidation and dissolution is made are not subject to the excise tax. Although such notice clarifies certain aspects of the excise tax, the interpretation and operation of aspects of the excise tax (including its application and operation with respect to SPACs) remain unclear and such interim operating rules are subject to change.

Because the application of this excise tax is not entirely clear, any redemption or other repurchase effected by us, in connection with a business combination, extension vote or otherwise, may be subject to this excise tax. Because any such excise tax would be payable by us and not by the redeeming holder, it could cause a reduction in the value of our shares of Class A Common Stock or cash available for distribution in a subsequent liquidation. Whether and to what extent we would be subject to the excise tax in connection with a business combination will depend on a number of factors, including (i) the structure of the business combination, (ii) the fair market value of the redemptions and repurchases in connection with the business combination, (iii) the nature and amount of any “PIPE” or other equity issuances in connection with the business combination (or any other equity issuances within the same taxable year of the business combination) and (iv) the content of any subsequent regulations, clarifications, and other guidance issued by the Treasury. Further, the application of the excise tax in respect of the distributions pursuant to a liquidation of a publicly traded U.S. corporation is uncertain and has not been addressed by the Treasury in regulations, and it is possible that the proceeds held in the Trust Account could be used to pay any excise tax owed by us in the event we are unable to complete a business combination in the required time and redeem 100% of our remaining Public Shares in accordance with the Certificate of Incorporation, in which case the amount that would otherwise be received by our public stockholders in connection with our liquidation would be reduced. However, to mitigate this uncertainty, the Company will not use any funds held in the Trust Account, including any interest thereon, to pay for any excise tax liabilities with respect to any redemptions of the Class A Common Stock, prior to or in connection with the Extension, a business combination or our liquidation.

Changes in laws or regulations, or a failure to comply with any laws and regulations, may adversely affect our business, including our ability to complete our initial business combination, and results of operations.

We are subject to laws and regulations enacted by national, regional and local governments. In particular, we are required to comply with certain SEC and other legal requirements. Compliance with, and monitoring of, applicable laws and regulations may be difficult, time consuming and costly. Those laws and regulations and their interpretation and application may also change from time to time and those changes could have a

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material adverse effect on our business, investments and results of operations. In addition, a failure to comply with applicable laws or regulations, as interpreted and applied, could have a material adverse effect on our business, including our ability to complete the Business Combination, and results of operations.

On March 30, 2022, the SEC issued proposed rules (the “2022 Proposed Rules”) relating to, among other items, enhancing disclosures in business combination transactions involving SPACs and private operating companies; amending the financial statement requirements applicable to transactions involving shell companies; effectively limiting the use of projections in SEC filings in connection with proposed business combination transactions; increasing the potential liability of certain participants in proposed business combination transactions; and the extent to which SPACs could become subject to regulation under the Investment Company Act. The 2022 Proposed Rules, if adopted, whether in the form proposed or in revised form, and certain positions and legal conclusions expressed by the SEC in connection with the 2022 Proposed Rules, may materially adversely affect our ability to complete the Business Combination and may increase the costs and time related thereto.

See also “— We may be subject to a new 1% U.S. federal excise tax in connection with redemptions of our shares of Class A Common stock” and “— If we are deemed to be an investment company under the Investment Company Act, we may be required to institute burdensome compliance requirements and our activities may be restricted, which may make it difficult for us to complete the Business Combination.”

If we are deemed to be an investment company under the Investment Company Act, we will be required to institute burdensome compliance requirements and our activities may be restricted, which will make it difficult for us to complete the Business Combination.

If we are deemed to be an investment company under the Investment Company Act, our activities will be restricted, including, without limitation, restrictions on the nature of our investments, restrictions on the issuance of securities, and restrictions on the enforceability of agreements entered into by us, each of which will make it difficult for us to complete the Business Combination. In addition, we may have imposed upon us burdensome requirements, including, without limitation, registration as an investment company with the SEC (which may be impractical and would require significant changes in, among other things, our capital structure); adoption of a specific form of corporate structure; and reporting, record keeping, voting, proxy and disclosure requirements and compliance with other rules and regulations that we are currently not subject to.

In order not to be regulated as an investment company under the Investment Company Act, unless we can qualify for an exclusion, we must ensure that we are engaged primarily in a business other than investing, reinvesting or trading in securities and that our activities do not include investing, reinvesting, owning, holding or trading “investment securities” constituting more than 40% of our total assets (exclusive of U.S. government securities and cash items) on an unconsolidated basis. Our business is to identify and complete a business combination and thereafter to operate the post-transaction business or assets for the long term. We do not plan to buy businesses or assets with a view to resale or profit from their resale. We do not plan to buy unrelated businesses or assets or to be a passive investor.

The 2022 Proposed Rules under the Investment Company Act would provide a safe harbor for SPACs from the definition of “investment company” under Section 3(a)(1)(A) of the Investment Company Act, provided that they satisfy certain conditions that limit a SPAC’s duration, asset composition, business purpose and activities. The duration component of the proposed safe harbor rule would require a SPAC to file a Current Report on Form 8-K with the SEC announcing that it has entered into an agreement with a target company (or companies) to engage in an initial business combination no later than 18 months after the effective date of the SPAC’s registration statement for its initial public offering. The SPAC would then be required to complete its initial business combination no later than 24 months after the effective date of its registration statement for its initial public offering. Although the 2022 Proposed Rules, including the proposed safe harbor rule, have not yet been adopted, there is uncertainty in the SEC’s view of the applicability of the Investment Company Act to a SPAC that does not complete its initial business combination within the proposed time frame set forth in the proposed safe harbor rule or otherwise falls outside of the other provisions of the safe harbor. We did not enter into a definitive business combination agreement within 18 months after the effective date of our registration statement relating to the initial public offering or complete our business combination within 24 months of such date.

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We do not believe that our principal activities currently subject us to the Investment Company Act. Moreover, the proceeds of our initial public offering held in the Trust Account have been invested only in United States “government securities” within the meaning of Section 2(a)(16) of the Investment Company Act having a maturity of 185 days or less, cash or in money market funds meeting certain conditions under Rule 2a-7 promulgated under the Investment Company Act which invest only in direct U.S. government treasury obligations. Pursuant to the trust agreement, the trustee is not permitted to invest in other securities or assets. By restricting the investment of the proceeds to these instruments and cash (including demand deposit accounts), and by having a business plan targeted at acquiring and growing businesses for the long-term (rather than on buying and selling businesses in the manner of a merchant bank or private equity fund), we do not believe we are an “investment company” within the meaning of the Investment Company Act. Despite these actions, we may nevertheless be deemed to be an unregistered investment company under the Investment Company Act. Limiting our investment as described above could cause the interest earned on the funds held in the Trust Account to be less than the returns that could otherwise be earned on such funds, and thereby reduce the dollar amount our public stockholders would receive upon any redemption or liquidation of the Trust Account.

Despite these actions, we may nevertheless be deemed an unregistered investment company under the Investment Company Act. If we were deemed to be an investment company for purposes of the Investment Company Act, we might be forced to abandon our efforts to complete an initial business combination and instead be required to liquidate. If we are required to liquidate, our investors would not be able to realize the benefits of owning stock in a successor operating business, including the potential appreciation in the value of our stock following such a transaction. If we are unable to complete a business combination on or before the Extended Date, our public stockholders may receive only approximately $10.00 per share on the liquidation of our Trust Account. In certain circumstances, our public stockholders may receive less than $10.00 per share on the redemption of their shares if we are unable to complete our initial business combination within the completion window.

Since Sponsor and our directors and officers will lose their entire investment in us if an initial business combination is not completed, they may have a conflict of interest in the approval of the proposals at the Special Meeting.

There will be no distribution from the Trust Account with respect to the founder shares or the Private Placement Shares (as defined below) in the event of our winding up. In the event of a liquidation, Sponsor and our officers and directors will not receive any monies held in the Trust Account as a result of either (i) their ownership of 12,500,000 founder shares that were issued to Sponsor prior to our initial public offering, which was consummated on July 12, 2021 (“initial public offering” or “IPO”) or (ii) their ownership of the 1,450,000 Private Placement Shares (as defined below). Such persons have acknowledged they have no right to any liquidating distributions with respect to such shares. As a result, all of such investments would expire worthless if an initial business combination is not consummated.

Additionally, such persons can earn a positive rate of return on their overall investment in the combined company after an initial business combination, even if other holders of our shares experience a negative rate of return, due to Sponsor having initially purchased the founder shares for an aggregate of $25,000. The personal and financial interests of Sponsor, and our directors and officers may have influenced their motivation in identifying and selecting Oklo as its target business combination and consummating the Business Combination and therefore may have interests different from, or in addition to, your interests as a stockholder in connection with the proposals at the Special Meeting.

The completion of the Business Combination is subject to a number of important conditions, and the Business Combination may be terminated before the completion of the Business Combination in accordance with its terms. As a result, there is no assurance that the Business Combination will be completed.

The completion of the Business Combination is subject to the satisfaction or waiver, as applicable, of a number of important conditions that are set forth in the Merger Agreement, including the approval of the Business Combination by AltC stockholders, the approval of the listing of the combined entity’s shares on New York Stock Exchange (the “NYSE”) or such other stock exchange as Oklo and AltC may mutually agree prior to the closing of the Business Combination, and several other customary closing conditions. If

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these conditions are not satisfied or, if the Business Combination is otherwise terminated by either AltC or Oklo, we are unlikely to find another target for a business combination before the Extended Date.

We have incurred and expect to continue to incur significant costs associated with the Business Combination. Whether or not the Business Combination is completed, the incurrence of these costs will reduce the amount of cash available to be used for other corporate purposes by us if the Business Combination is not completed.

We expect to incur significant transaction and transition costs associated with the Business Combination and operating as a public company following the closing of the Business Combination. We may also incur additional costs to retain key employees. Certain transaction expenses incurred in connection with the Business Combination, including all legal, accounting, consulting, investment banking and other fees, expenses and costs, will be paid by the combined company at or following the closing of the Business Combination. Even if the Business Combination is not completed, we expect to incur approximately $5,000,000 in expenses in the aggregate. These expenses will reduce the amount of cash available to be used for other corporate purposes by us if the Business Combination is not completed.

The NYSE may delist our securities from trading on its exchange, which could limit investors’ ability to make transactions in our securities and subject us to additional trading restrictions.

Our shares of Class A Common Stock are listed on the NYSE. We cannot assure you that our securities will continue to be listed on the NYSE in the future, following the Extension or prior to a business combination. In order to continue listing our securities on the NYSE prior to the Business Combination, we must maintain certain financial, distribution and stock price levels. In general, we must maintain a minimum number of holders of our securities. Additionally, in connection with the Business Combination, we will be required to demonstrate compliance with the NYSE’s initial listing requirements, which are more rigorous than the NYSE’s continued listing requirements, in order to continue to maintain the listing of our securities on the NYSE. For instance, our stock price would generally be required to be at least $4 per share. We cannot assure you that we will be able to meet those initial listing requirements at that time.

If the NYSE delists any of our securities from trading on its exchange and we are not able to list such securities on another national securities exchange, we expect such securities could be quoted on an over-the-counter market. If this were to occur, we could face significant material adverse consequences, including:

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a limited availability of market quotations for our securities;

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reduced liquidity for our securities;

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a determination that our shares of Class A Common Stock should be classified as a “penny stock” which will require brokers trading in our shares of Class A Common Stock to adhere to more stringent rules and possibly result in a reduced level of trading activity in the secondary trading market for our securities;

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a limited amount of news and analyst coverage; and

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a decreased ability to issue additional securities or obtain additional financing in the future.

The National Securities Markets Improvement Act of 1996, which is a federal statute, prevents or preempts the states from regulating the sale of certain securities, which are referred to as “covered securities.” Because our shares of Class A Common Stock are listed on the NYSE, our shares of Class A Common Stock qualify as covered securities under such statute. Although the states are preempted from regulating the sale of our securities, the federal statute does allow the states to investigate companies if there is a suspicion of fraud, and, if there is a finding of fraudulent activity, then the states can regulate or bar the sale of covered securities in a particular case. While we are not aware of a state having used these powers to prohibit or restrict the sale of securities issued by blank check companies, other than the State of Idaho, certain state securities regulators view blank check companies unfavorably and might use these powers, or threaten to use these powers, to hinder the sale of securities of blank check companies in their states. Further, if we were no longer listed on the NYSE, our securities would not qualify as covered securities under such statute and we would be subject to regulation in each state in which we offer our securities.

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QUESTIONS AND ANSWERS ABOUT THE SPECIAL MEETING

The questions and answers below highlight only selected information from this Proxy Statement and only briefly address some commonly asked questions about the Special Meeting and the proposals to be presented at the Special Meeting. The following questions and answers do not include all the information that is important to AltC stockholders. Stockholders are urged to read carefully this entire Proxy Statement, including Annex A and the other documents referred to herein, to fully understand the proposals to be presented at the Special Meeting and the voting procedures for the Special Meeting.

Why am I receiving this proxy statement?

This Proxy Statement and the enclosed proxy card are being sent to you in connection with the solicitation of proxies by the Board for use at the Special Meeting to be held virtually on October 5, 2023, or at any adjournments or postponements thereof. This Proxy Statement summarizes the information that you need to make an informed decision on the proposals to be considered at the Special Meeting.

AltC is a blank check company incorporated as a Delaware corporation for the purpose of effecting a merger, capital stock exchange, asset acquisition, stock purchase, reorganization or other similar business combination with one or more businesses. On July 12, 2021, AltC consummated its initial public offering of 50,000,000 shares of Class A Common Stock. Like most blank check companies, the Certificate of Incorporation provides for the return of the initial public offering proceeds held in trust to the holders of the outstanding shares of Class A Common Stock, sold in the initial public offering if there is no qualifying business combination(s) consummated on or before the Termination Date.

AltC believes that it is in the best interests of AltC’s stockholders to continue AltC’s existence until the Extended Date, if necessary, in order to allow AltC additional time to complete the Business Combination and is therefore holding this Special Meeting.

What are the specific proposals on which I am being asked to vote at the Special Meeting?

AltC stockholders are being asked to consider and vote on the following proposals:

Proposal No. 1 — The “Extension Amendment Proposal” — To amend the Certificate of Incorporation to extend the date by which AltC has to consummate a business combination (the “Extension”) from October 12, 2023, or the “Termination Date,” to July 12, 2024 (or such earlier date as determined by AltC’s board of directors (the “Board”)) (such date, the “Extended Date” and, such proposal, the “Extension Amendment Proposal”); and

Why is AltC proposing the Extension Amendment Proposal and the Adjournment Proposal?

The Certificate of Incorporation provides for the return of the initial public offering proceeds held in trust to the holders of Public Shares sold in the initial public offering if there is no qualifying business combination(s) consummated on or before the Termination Date. The purpose of the Extension Amendment Proposal and, if necessary, the Adjournment Proposal, is to allow AltC additional time to complete the Business Combination pursuant to the Merger Agreement.

The Board believes that it is in the best interests of AltC stockholders that the Extension be implemented so that AltC will have additional time to complete the Business Combination. Without the Extension, AltC would not be able to complete the Business Combination on or before the Termination Date. If that were to occur, AltC would be precluded from completing the Business Combination and would be forced to liquidate even if AltC’s stockholders are otherwise in favor of consummating the Business Combination. If the Extension Amendment Proposal is not approved and the Business Combination is

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not completed on or before the Termination Date, AltC will: (i) cease all operations except for the purpose of winding up, (ii) as promptly as reasonably possible but not more than ten business days thereafter subject to lawfully available funds therefor, redeem 100% of the Public Shares in consideration of a per share price, payable in cash, equal to the quotient obtained by dividing (A) the aggregate amount then on deposit the Trust Account, including interest (net of amounts withdrawn to fund AltC’s working capital requirements, subject to an annual limit of $1,000,000 (but notwithstanding the annual limitation, such withdrawals can only be made from interest and not from the principal held in the Trust Account), and amounts withdrawn as Permitted Withdrawals and less up to $100,000 of such net interest to pay dissolution expenses), by (B) the total number of then outstanding Public Shares, which redemption will completely extinguish rights of the holders of Public Shares (including the right to receive further liquidating distributions, if any), subject to applicable law, and (iii) as promptly as reasonably possible following such redemption, subject to the approval of the remaining stockholders and the Board in accordance with applicable law, dissolve and liquidate, subject in each case to AltC’s obligations under the DGCL to provide for claims of creditors and other requirements of applicable law.

AltC believes that given AltC’s expenditure of time, effort and money on the Business Combination, circumstances warrant ensuring that AltC is in the best position possible to complete the Business Combination and that it is in the best interests of AltC’s stockholders that AltC obtain the Extension. AltC believes the Business Combination will provide significant benefits to its stockholders. For more information about the Business Combination, see our Current Report on Form 8-K filed with the SEC on July 11, 2023, and our other filings with the SEC.

You are not being asked to vote on the Business Combination at the Special Meeting. The vote by AltC stockholders on the Business Combination will occur at the separate Business Combination Special Meeting of AltC stockholders and the solicitation of proxies from AltC stockholders in connection with such separate Business Combination Special Meeting, and the related right of AltC stockholders to redeem in connection with the Business Combination (which is a separate right to redeem in addition to the right to redeem in connection with the Extension Amendment Proposal), will be addressed in a Registration Statement on Form S-4 to be filed by AltC at a later date. If you want to ensure your Public Shares are redeemed in the event either the Extension Amendment Proposal is implemented or the Business Combination is completed, you should elect to redeem your Public Shares in connection with either the Special Meeting or the Business Combination Special Meeting, respectively.

Each public stockholder may make an Election to redeem their Public Shares for a per-share price (the “Per-Share Redemption Price”), payable in cash, equal to the aggregate amount then on deposit in the Trust Account, including interest earned on the funds held in the Trust Account (as of the Record Date) and not previously released to us but net of taxes payable, divided by the number of then outstanding Public Shares, regardless of whether such stockholder votes “FOR” or “AGAINST” the Extension Amendment Proposal.

Immediately following the Redemption Deadline, a public stockholder may make an Election Reversal. See “The Extension Amendment Proposal — Redemption Withdrawal Procedures.”

If the Extension Amendment Proposal is approved and the Extension is completed, we will, pursuant to the investment management trust agreement, remove from the Trust Account an amount (the “Withdrawal Amount”) equal to the number of Public Shares properly redeemed (after taking into account any Election Reversals) in connection with the stockholder vote on the Extension Amendment Proposal multiplied by the Per-Share Redemption Price (the “Withdrawal”) and retain the remainder of the funds in the Trust Account for our use in connection with consummating an initial business combination on or before the Extended Date.

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If the Extension Amendment Proposal is approved and the Extension is implemented, the removal of the Withdrawal Amount from the Trust Account in connection with the Election (after taking into account any Election Reversals) will reduce the amount held in the Trust Account following the Election. We cannot predict the amount that will remain in the Trust Account following the completion of the Extension and the amount remaining in the Trust Account may be only a small fraction of the approximately $516,729,800 (including interest not previously released to us but net of taxes payable) that was in the Trust Account as of the Record Date. In such event, we may need to obtain additional funds to complete an initial business combination, and there can be no assurance that such funds will be available on terms acceptable to the parties or at all. AltC will not proceed with the Extension if the number of redemptions (after taking into account any Election Reversals) of our Public Shares (after taking into account any Election Reversals) causes AltC to have less than $5,000,001 of net tangible assets following approval of the Extension Amendment Proposal. The Merger Agreement provides that the consummation of the Business Combination is conditioned upon, among other things, AltC having at least $5,000,001 of net tangible assets as of the closing of the Business Combination. Additionally, the obligations of Oklo to complete the Business Combination are conditioned upon, among other things, the amount of cash available in the Trust Account (including, the net proceeds of any incremental financing raised by AltC or Oklo in connection with the transactions contemplated by the Merger Agreement) being at least $250,000,000, after reduction for redemptions made in connection with the Business Combination Special Meeting and any excise tax payable by AltC, but before giving effect to the payment of transaction expenses.

What vote is required to approve the proposals presented at the Special Meeting?

The approval of the Extension Amendment Proposal requires the affirmative vote of the holders of at least 65% of all the outstanding shares of Common Stock as of the Record Date. A stockholder’s failure to vote by proxy or to vote in person at the Special Meeting will not be counted towards the number of Common Stock required to validly establish a quorum, and if a valid quorum is otherwise established, such failure to vote will have the effect of voting “AGAINST” the Extension Amendment Proposal. Abstentions (but not broker non-votes), while considered present for the purposes of establishing a quorum, will have the effect of voting “AGAINST” the Extension Amendment Proposal. The presence, in person or by proxy, at the Special Meeting of the holders of shares of outstanding Common Stock representing a majority of the voting power of all issued and outstanding shares of Common Stock entitled to vote as of the Record Date at the Special Meeting shall constitute a quorum for the vote on the Extension Amendment Proposal.

Approval of the Adjournment Proposal requires the affirmative vote of a majority of the votes cast by the holders of the shares of Common Stock, voting together as a single class, present in person or represented by proxy at the Special Meeting and entitled to vote thereon. Accordingly, a stockholder’s failure to vote by proxy or to vote in person at the Special Meeting will not be counted towards the number of shares of Common Stock required to validly establish a quorum. However, if a valid quorum is otherwise established, such failure to vote will have no effect on the outcome of any vote on the Adjournment Proposal. Abstentions (but not broker non-votes), while considered present for the purposes of establishing a quorum, will not count as a vote cast at the Special Meeting and will have no effect on the outcome of any vote on the Adjournment Proposal. The presence, in person or by proxy, at the Special Meeting of the holders of shares of outstanding Common Stock representing a majority of the voting power of all issued and outstanding shares of Common Stock entitled to vote as of the Record Date at the Special Meeting shall constitute a quorum for the vote on the Adjournment Proposal.

Why should I vote “FOR” the Extension Amendment Proposal?

AltC believes stockholders will benefit from AltC consummating the Business Combination and is proposing the Extension Amendment Proposal to extend the date by which AltC has to complete a business combination until the Extended Date. The Extension would give AltC additional time to complete the Business Combination.

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AltC would not be able to complete the Business Combination on or before the Termination Date. If that were to occur, AltC would be precluded from completing the Business Combination and would be forced to liquidate even if AltC stockholders are otherwise in favor of consummating the Business Combination. If the Extension Amendment Proposal is not approved and the Business Combination is not completed on or before the Termination Date, AltC will: (i) cease all operations except for the purpose of winding up, (ii) as promptly as reasonably possible but not more than ten business days thereafter subject to lawfully available funds therefor, redeem 100% of the Public Shares in consideration of a per share price, payable in cash, equal to the quotient obtained by dividing (A) the aggregate amount then on deposit in the Trust Account, including interest (net of amounts withdrawn as Permitted Withdrawals and less up to $100,000 of such net interest to pay dissolution expenses), by (B) the total number of then outstanding Public Shares, which redemption will completely extinguish rights of the Public Stockholders (including the right to receive further liquidating distributions, if any), subject to applicable law, and (iii) as promptly as reasonably possible following such redemption, subject to the approval of the remaining stockholders and the Board in accordance with applicable law, dissolve and liquidate, subject in each case to AltC’s obligations under the DGCL to provide for claims of creditors and other requirements of applicable law.

Why should I vote “FOR” the Adjournment Proposal?

If the Adjournment Proposal is not approved by AltC’s stockholders, the Board may not be able to adjourn the Special Meeting to a later date or dates in the event that there are insufficient votes for, or otherwise in connection with, the approval of the Extension Amendment Proposal or if AltC determines that additional time is necessary to effectuate the Extension.

If presented, the Board unanimously (of those who voted) recommends that you vote in favor of the Adjournment Proposal, but expresses no opinion as to whether you should redeem your Public Shares.

When would the Board abandon the Extension Amendment?

Our Board will abandon the Extension Amendment if our stockholders do not approve the Extension Amendment Proposal. In addition, notwithstanding stockholder approval of the Extension Amendment Proposal, our Board will retain the right to abandon and not implement the Extension Amendment at any time without any further action by our stockholders.

How will Sponsor and AltC’s directors and officers vote?

Sponsor and AltC’s directors and officers have agreed to vote any shares of Common Stock over which they have voting control in favor of the Extension Amendment Proposal and, if necessary, the Adjournment Proposal.

Sponsor and AltC’s directors and officers and their respective affiliates are not entitled to redeem any shares of Common Stock in connection with the Extension Amendment Proposal. On the Record Date, Sponsor and AltC’s directors and officers and their respective affiliates beneficially owned and were entitled to vote an aggregate of 13,950,000 shares of Common Stock, representing approximately 21.8% of AltC’s issued and outstanding shares of Common Stock.

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Sponsor and the Company’s directors, officers and advisors, or any of their respective affiliates, may purchase Public Shares in privately negotiated transactions or in the open market prior to the Special Meeting, and except as described on our Current Report on Form 8-K filed with the SEC on July 11, 2023, describing the material terms of the Business Combination, they are under no obligation to do so. Any such purchases that are completed after the Record Date may include an agreement with a selling stockholder that such stockholder, for so long as it remains the record holder of the shares of Common Stock in question, will vote in favor of the proposals and/or will not exercise its redemption rights with respect to the shares of Common Stock so purchased. The purpose of such purchases and other transactions would be to increase the likelihood that the proposals to be voted upon at the Special Meeting are approved by the requisite number of votes. In the event that such purchases do occur, the purchasers may seek to purchase shares from stockholders who would otherwise have voted against the proposals and elected to redeem their shares for a portion of the Trust Account. Any such privately negotiated purchases may be effected at purchase prices that are below or in excess of the per-share pro rata portion of the Trust Account. Any Public Shares held by or subsequently purchased by our affiliates may be voted in favor of the proposals. None of Sponsor or the Company’s directors, officers or advisors or any of their respective affiliates may make any such purchases when they are in possession of any material nonpublic information not disclosed to the seller or during a restricted period under Regulation M under the Securities Exchange Act of 1934 (the “Exchange Act”).

What if I do not want to vote “FOR” the Extension Amendment Proposal or the Adjournment Proposal?

If you do not want the Extension Amendment Proposal or the Adjournment Proposal to be approved, you may “ABSTAIN”, not vote, or vote “AGAINST” such proposal.

If you fail to vote by proxy or to vote in person at the Special Meeting, your shares will not be counted in connection with the determination of whether a valid quorum is established and, if a valid quorum is otherwise established, such failure to vote will have the effect of voting “AGAINST” the Extension Amendment Proposal and will have no effect on the outcome of any vote on the Adjournment Proposal.

If you vote to “ABSTAIN” or if you do not provide instructions with your proxy card to your broker, bank or nominee, such abstentions (but not broker non-votes) will be counted in connection with the determination of whether a valid quorum is established, and will have the effect of voting “AGAINST” the Extension Amendment Proposal.

If the Extension Amendment Proposal is approved, the Adjournment Proposal will not be presented for a vote unless AltC determines that additional time is necessary to effectuate the Extension.

What happens if the Extension Amendment Proposal is not approved?

If there are insufficient votes to approve the Extension Amendment Proposal, AltC may put the Adjournment Proposal to a vote in order to seek additional time to obtain sufficient votes in support of the Extension. The Board will abandon the Extension Amendment if our stockholders do not approve the Extension Amendment Proposal.

If the Extension Amendment Proposal is not approved and the Business Combination is not completed on or before the Termination Date, AltC will: (i) cease all operations except for the purpose of winding up, (ii) as promptly as reasonably possible but not more than ten business days thereafter subject to lawfully available funds therefor, redeem 100% of the Public Shares in consideration of a per share price, payable in cash, equal to the quotient obtained by dividing (A) the aggregate amount then on deposit in the Trust Account, including interest (net of amounts withdrawn as Permitted Withdrawals and less up to $100,000 of such net interest to pay dissolution expenses), by (B) the total number of then outstanding Public Shares, which redemption will completely extinguish rights of the public stockholders (including the right to receive further liquidating distributions, if any), subject to applicable law, and (iii) as promptly as reasonably possible following such redemption, subject to the approval of the remaining stockholders and the Board in accordance with applicable law, dissolve and liquidate, subject in each case to AltC’s obligations under the DGCL to provide for claims of creditors and other requirements of applicable law.

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Sponsor and the officers and directors of AltC have each acknowledged they have no right to any liquidating distributions with respect to the 13,950,000 shares of Common Stock held by them on the Record Date. AltC will pay any costs from its remaining assets outside of the Trust Account.

If the Extension Amendment Proposal is approved, what happens next?

On July 11, 2023, we entered into the Merger Agreement with respect to the Business Combination. We are seeking the Extension Amendment to provide us with additional time to complete the Business Combination. Our efforts to complete the Business Combination will involve:

•

filing the Business Combination Registration Statement;

•

establishing a meeting date and record date for the Business Combination Special Meeting, and distributing proxy materials to stockholders;

•

attempting to ensure that the conditions to the closing of the Business Combination are satisfied; and

•

holding the Business Combination Special Meeting.

We are seeking approval of the Extension Amendment Proposal because we will not be able to complete all of the tasks listed above prior to October 12, 2023. If the Extension Amendment Proposal is approved, we expect to seek stockholder approval of the Business Combination. If stockholders approve the Business Combination, we expect to complete the Business Combination as soon as practicable following such stockholder approval.

Upon approval of the Extension Amendment Proposal by holders of at least 65% of the Common Stock outstanding as of the Record Date, we expect to file an amendment to the charter with the Secretary of State of the State of Delaware in the form set forth in Annex A hereto. We will remain a reporting company under the Exchange Act and our shares of Common Stock are expected to remain publicly traded.

If the Extension Amendment Proposal is approved, the removal of the Withdrawal Amount from the Trust Account will reduce the amount remaining in the Trust Account and increase the percentage interest of our shares of Common Stock held by Sponsor as a result of its ownership of shares of Class A Common Stock and Class B Common Stock.

Where will I be able to find the voting results of the Special Meeting?

We will announce preliminary voting results at the Special Meeting. We will also disclose voting results on a Current Report on Form 8-K that we will file with the SEC within four business days after the Special Meeting. If final voting results are not available to us in time to file a Current Report on Form 8-K within four business days after the Special Meeting, we will file a Current Report on Form 8-K to publish preliminary results and will provide the final results in an amendment to such Current Report on Form 8-K as soon as they become available.

Would I still be able to exercise my redemption rights if I vote “AGAINST” the Business Combination?

Unless you elect to redeem your Public Shares at this time and do not make an Election Reversal, you will be able to vote on the Business Combination at the Business Combination Special Meeting if you are a stockholder on the Record Date for the Business Combination Special Meeting. If you disagree with the Business Combination, you will retain your right to redeem your Public Shares upon consummation of the Business Combination in connection with the Business Combination Special Meeting, subject to any limitations set forth in our Certificate of Incorporation.

If AltC does not implement the Extension, it will not redeem any Public Shares submitted for Redemption in connection with the Special Meeting.

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May I change my vote after I have mailed my signed proxy card?

Yes. You may change your vote by sending a later-dated, signed proxy card to AltC’s Chief Financial Officer at the address listed below prior to the vote at the Special Meeting, or attend the Special Meeting and vote in person online. You also may revoke your proxy by sending a notice of revocation to AltC’s Chief Financial Officer, provided such revocation is received prior to the vote at the Special Meeting. If your shares are held in street name by a broker or other nominee, you must contact the broker or nominee to change your vote.

How are votes counted?

Votes will be counted by the inspector of election appointed for the Special Meeting, who will separately count “FOR” and “AGAINST” votes, “ABSTAIN” and broker non-votes. The Extension Amendment Proposal must be approved by the affirmative vote of the holders of at least 65% of all then outstanding shares of Common Stock as of the Record Date. Approval of the Adjournment Proposal requires the affirmative vote of a majority of the votes cast by the holders of the shares of Common Stock, voting together as a single class, present in person or represented by proxy at the Special Meeting and entitled to vote thereon. With respect to the Extension Amendment Proposal, abstentions (but not broker non-votes), while considered present for the purposes of establishing a quorum, will have the effect of voting “AGAINST” the Extension Amendment Proposal. With respect to the Adjournment Proposal, abstentions (but not broker non-votes), while considered present for the purposes of establishing a quorum, will not count as a vote cast at the Special Meeting and will have no effect on the outcome of any vote on the Adjournment Proposal.

If you hold shares beneficially in street name and do not provide your broker with voting instructions, your shares may constitute “broker non-votes.” Broker non-votes occur when brokers or others hold shares in street name for a beneficial owner that has not provided instructions on how to vote on a particular matter. Matters on which a broker is not permitted to vote without instructions from the beneficial owner and instructions are not given are referred to as “non-routine” matters. The Extension Amendment Proposal and the Adjournment Proposal are considered “non-routine.” Accordingly, your broker, bank or nominee may not vote your shares with respect to such proposals without receiving voting instructions. In tabulating the voting result for the proposals, shares that constitute broker non-votes and abstentions are not considered votes cast.

How can I attend the Special Meeting?

You may attend the Special Meeting and vote your shares in person online during the Special Meeting via live webcast by visiting https://www.cstproxy.com/altcacquisitioncorp/2023. You will need the 12-digit meeting control number that is printed on your proxy card to enter the Special Meeting. If you are a beneficial owner and do not have your 16-digit meeting control number, contact your banker, broker or other nominee. Please note that you will not be able to physically attend the Special Meeting in person, but may attend the Special Meeting in person online.

What constitutes a quorum at the Special Meeting?

A quorum will be present at the Special Meeting if a majority of the shares of Common Stock outstanding and entitled to vote at the Special Meeting is represented in person online or by proxy. As of the Record Date, 31,975,001 shares of Common Stock would be required to achieve a quorum.

Your shares will be counted towards the quorum only if you submit a valid proxy (or your broker, bank or other nominee submits one on your behalf) or if you vote in person online at the Special Meeting.

Abstentions (but not broker non-votes) will be counted towards the quorum requirement. If there is no quorum, a majority of the shares represented by stockholders present in person online at the Special Meeting or by proxy may authorize adjournment of the Special Meeting to another date.

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How do I vote?

If you were a holder of record of shares of Common Stock on the Record Date, you may vote with respect to the applicable proposals in person online at the Special Meeting, by internet, by phone, or by completing, signing, dating and returning the enclosed proxy card in the postage-paid envelope provided. If you choose to vote by internet, visit https://www.cstproxy.com/altcacquisitioncorp/2023, 24 hours a day, seven days a week, until 11:59 p.m. Eastern Time on October 4, 2023 (have your proxy card in hand when you visit the website). If you choose to vote by phone, call toll-free (within the U.S. or Canada) 1 800-450-7155 (have your proxy card in hand when you call). If you choose to participate in the Special Meeting, you can vote your shares electronically during the Special Meeting via live webcast by visiting https://www.cstproxy.com/altcacquisitioncorp/2023. You will need the 12-digit meeting control number that is printed on your proxy card to enter the Special Meeting. AltC recommends that you log in at least 15 minutes before the Special Meeting to ensure you are logged in when the Special Meeting starts.

If on the Record Date your shares were held, not in your name, but rather in an account at a brokerage firm, bank, dealer, or other similar organization, then you are the beneficial owner of shares held in “street name” and these proxy materials are being forwarded to you by that organization. As a beneficial owner, you have the right to direct your broker or other agent on how to vote the shares in your account. You are also invited to attend the Special Meeting in person online. However, since you are not the stockholder of record, you may not vote your shares in person online at the Special Meeting unless you first request and obtain a valid legal proxy from your broker or other agent. You must then e-mail a copy (a legible photograph is sufficient) of your legal proxy to Continental Stock Transfer & Trust Company at proxy@continentalstock.com. Beneficial owners who e-mail a valid legal proxy will be issued a 12-digit meeting control number that will allow them to register to attend and participate in the Special Meeting. Beneficial owners who wish to attend the Special Meeting in person online should contact Continental Stock Transfer & Trust Company no later than October 2, 2023 to obtain this information.

Does the Board recommend voting “FOR” the approval of the Extension Amendment Proposal and the Adjournment Proposal?

Yes. After careful consideration of the terms and conditions of the Extension Amendment Proposal, the Board unanimously (of those who voted) has determined that the Extension Amendment Proposal is in the best interests of AltC and its stockholders. The Board unanimously (of those who voted) recommends that AltC’s stockholders vote “FOR” the Extension Amendment Proposal.

Additionally, the Board unanimously (of those who voted) has determined that the Adjournment Proposal is in the best interests of AltC and its stockholders and recommends that AltC’s stockholders vote “FOR” the Adjournment Proposal.

What interests do AltC’s directors and officers have in the approval of the Extension Amendment Proposal?

AltC’s directors and executive officers and their respective affiliates may have interests that are different from, in addition to or in conflict with, yours. The Board was aware of and considered these interests to the extent such interests existed at the time, among other matters, in making their recommendation that you vote in favor of the approval of the Extension Amendment Proposal. See the section entitled “Special Meeting of AltC Stockholders — Interests of Sponsor and AltC’s Directors and Officers” in this Proxy Statement.

Do I have appraisal rights or dissenters’ rights if I object to the Extension Amendment Proposal?

No. There are no appraisal rights available to AltC’s stockholders in connection with the Extension Amendment Proposal under the DGCL.

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What do I need to do now?

You are urged to read carefully and consider the information contained in this Proxy Statement, including Annex A, and to consider how the Extension Amendment Proposal and the Adjournment Proposal will affect you as a stockholder. You should then vote as soon as possible in accordance with the instructions provided in this Proxy Statement and on the enclosed proxy card or, if you hold your shares through a brokerage firm, bank or other nominee, on the voting instruction form provided by the broker, bank or nominee.

How are the funds in the Trust Account currently being held?

With respect to the regulation of special purpose acquisition companies (“SPACs”), like the Company, on March 30, 2022, the SEC issued proposed rules (the “SPAC Rule Proposals”) relating to, among other items, disclosures in business combination transactions involving SPACs and private operating companies; the condensed financial statement requirements applicable to transactions involving shell companies; the use of projections by SPACs in SEC filings in connection with proposed business combination transactions; the potential liability of certain participants in proposed business combination transactions; and the extent to which SPACs could become subject to regulation under the Investment Company Act of 1940, as amended, including a proposed rule that would provide SPACs a safe harbor from treatment as an investment company if they satisfy certain conditions that limit a SPAC’s duration, asset composition, business purpose and activities.

With regard to the SEC’s investment company proposals included in the SPAC Rule Proposals, the funds in the Trust Account were, from the time beginning with the consummation of the Company’s initial public offering, held only in U.S. government treasury bills with a maturity of 185 days or less, cash or in money market funds investing solely in U.S. Treasuries. To mitigate the risk of being viewed as operating an unregistered investment company (including pursuant to the subjective test of Section 3(a)(1)(A) of the Investment Company Act of 1940), AltC instructed Continental Stock Transfer & Trust Company, the trustee managing the Trust Account, to hold all funds in the Trust Account in cash (which may include demand deposit accounts) until the earlier of consummation of our initial business combination or liquidation. Limiting our investment as described above could cause the interest earned on the funds held in the Trust Account to be less than the returns that could otherwise be earned on such funds, and thereby reduce the dollar amount our public stockholders would receive upon any redemption or liquidation of the Trust Account.

How do I exercise my redemption rights?

In order to exercise your redemption rights, you must, prior to 5:00 p.m. Eastern Time on October 3, 2023 (two business days before the Special Meeting), (i) submit a written request to AltC’s transfer agent that AltC redeem your Public Shares for cash and (ii) deliver your stock to AltC’s transfer agent physically or electronically through The Depository Trust Company (“DTC”). The address of Continental Stock Transfer & Trust Company, AltC’s transfer agent, is listed under the question “Who can help answer my questions?” below. AltC requests that any requests for redemption include the identity of the beneficial owner making such request. Electronic delivery of your stock generally will be faster than delivery of physical stock certificates.

A physical stock certificate will not be needed if your stock is delivered to AltC’s transfer agent electronically. In order to obtain a physical stock certificate, a stockholder’s broker and/or clearing broker, DTC and AltC’s transfer agent will need to act to facilitate the request. It is AltC’s understanding that stockholders should generally allot at least two weeks to obtain physical certificates from the transfer agent. However, because AltC does not have any control over this process or over the brokers or DTC, it may take significantly longer than two weeks to obtain a physical stock certificate. If it takes longer than anticipated to obtain a physical certificate, stockholders who wish to redeem their shares may be unable to obtain physical certificates by the deadline for exercising their redemption rights and thus will be unable to redeem their shares.

Any demand for redemption, once made, may be withdrawn at any time until the deadline for exercising redemption requests, with AltC’s consent. If you delivered your shares for redemption to AltC’s

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transfer agent and decide within the required timeframe not to exercise your redemption rights, you may request that AltC’s transfer agent return the shares (physically or electronically). You may make such request by contacting AltC’s transfer agent at the phone number or address listed under the question “Who can help answer my questions?”

How do I make an Election Reversal with respect to my public shares?

Immediately following the deadline to make an Election (which is 5:00 P.M. Eastern Time on October 3, 2023, the date that is two business days prior to the scheduled vote at the Special Meeting), a public stockholder that desires to withdraw its Election may effectuate an Election Reversal. In order to effectuate an Election Reversal, you must request that the transfer agent return the shares (physically or electronically) as soon as possible after the deadline to make an Election. Such written request shall include your legal name, phone number and address of the beneficial owner of the shares for which reversal is requested. If you hold the shares in street name, you will need to instruct the account executive at your bank or broker to request reversal of the tender from the transfer agent.

We will not proceed with the Extension if the number of redemptions of our Public Shares (after taking into account any Election Reversals) causes AltC to have less than $5,000,001 of net tangible assets following approval of the Extension Amendment Proposal. The Merger Agreement provides that the consummation of the Business Combination is conditioned upon, among other things, AltC having at least $5,000,001 of net tangible assets as of the closing of the Business Combination. Additionally, the obligations of Oklo to complete the Business Combination are conditioned upon, among other things, the amount of cash available in the Trust Account (including, the net proceeds of any incremental financing raised by AltC or Oklo in connection with the transactions contemplated by the Merger Agreement) being at least $250,000,000, after reduction for redemptions made in connection with the Business Combination Special Meeting and any excise tax payable by AltC, but before giving effect to the payment of transaction expenses.

Notwithstanding stockholder approval of the Extension Amendment Proposal or the number of Elections (taking into account any Election Reversals) by our public stockholders, the Board will retain the right to abandon the Extension Amendment Proposal or postpone or cancel the special meeting at any time and for any reason without any further action by our stockholders.

What should I do if I receive more than one set of voting materials for the Special Meeting?

You may receive more than one set of voting materials, including multiple copies of this Proxy Statement and multiple proxy cards or voting instruction cards. For example, if you hold your shares in more than one brokerage account, you will receive a separate voting instruction card for each brokerage account in which you hold shares. If you are a holder of record and your shares are registered in more than one name, you will receive more than one proxy card. Please complete, sign, date and return each proxy card and voting instruction card that you receive in order to cast your vote with respect to all of your shares.

Who will solicit and pay the cost of soliciting proxies for the Special Meeting?

AltC will pay the cost of soliciting proxies for the Special Meeting. AltC has engaged Morrow Sodali LLC (“Morrow”) to assist in the solicitation of proxies for the Special Meeting. AltC has agreed to pay Morrow a fee of up to $30,000 in connection with the Extension Amendment. AltC will reimburse Morrow for reasonable and customary documented out-of-pocket expenses and will indemnify Morrow and its directors, officers, employees and agents against certain claims, liabilities, losses, damages and expenses. AltC will also reimburse banks, brokers and other custodians, nominees and fiduciaries representing beneficial owners of Public Shares for their expenses in forwarding soliciting materials to beneficial owners of Public Shares and in obtaining voting instructions from those owners. AltC’s directors, officers and employees may also solicit proxies by telephone, by facsimile, by mail, on the Internet or in person. They will not be paid any additional amounts for soliciting proxies.

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Who can help answer my questions?

If you have questions about the proposals, or if you need additional copies of this Proxy Statement or the proxy card you should contact our proxy solicitor at:

Morrow Sodali LLC
333 Ludlow Street, 5th Floor
South Tower, Stamford CT 06902
Toll-Free (800) 662-5200 or (203) 658-9400
E-mail: ALCC.info@morrowsodali.com

You may also contact AltC at:

AltC Acquisition Corp.
640 Fifth Avenue — 12th Floor
New York, New York 10019
Attention: Jay Taragin, Chief Financial Officer
E-mail: Jay.Taragin@mkleinandcompany.com

To obtain timely delivery, AltC’s stockholders must request the materials no later than five business days prior to the Special Meeting.

You may also obtain additional information about AltC from documents filed with the SEC by following the instructions in the section entitled “Where You Can Find More Information.”

If you intend to seek redemption of your Public Shares, you will need to send a letter demanding redemption and deliver your stock (either physically or electronically) to AltC’s transfer agent prior to 5:00 p.m., Eastern Time, on the second business day prior to the Special Meeting. If you have questions regarding the certification of your position or delivery of your stock, please contact:

Continental Stock Transfer & Trust Company
1 State Street, 30th Floor
New York, New York 10004
Attention: SPAC Administration Team
Email: spacredemptions@continentalstock.com

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BACKGROUND

General

AltC is a blank check company formed as a Delaware corporation for the purpose of effecting a merger, capital stock exchange, asset acquisition, stock purchase, reorganization or similar business combination with one or more businesses. On July 12, 2021, AltC consummated its initial public offering of 50,000,000 Public Shares, which included the full exercise of the underwriters’ over-allotment option. The Public Shares were sold at a price of $10.00 per Public Share, generating gross proceeds to the Company of $500,000,000.

Simultaneously with the closing of the initial public offering, Sponsor purchased an aggregate of 1,450,000 shares of Class A Common Stock in a private placement (each, a “Private Placement Share” and collectively, the “Private Placement Shares”), generating gross proceeds of $14,500,000 ($10.00 per Private Placement Share). The proceeds from the sale of the Private Placement Shares were added to the proceeds from the initial public offering held in the Trust Account.

The Proposed Business Combination

As previously announced, we entered into the Merger Agreement on July 11, 2023. Pursuant to the Merger Agreement, the parties agreed, subject to the terms and conditions of the Merger Agreement, to effect the Business Combination. The Board currently believes that there will not be sufficient time before October 12, 2023, to complete the Business Combination. Accordingly, the Board believes that in order to be able to complete the Business Combination, we will need to obtain the Extension. Without the Extension, we believe that we will not be able to complete the Business Combination on or before October 12, 2023. If that were to occur, we would be precluded from completing the Business Combination and would be forced to liquidate even if our stockholders are otherwise in favor of consummating the Business Combination. For more information about the Business Combination, see our Current Report on Form 8-K filed with the SEC on July 11, 2023, and our other filings with the SEC.

We believe that the foregoing provision in the Certificate of Incorporation was included to protect AltC stockholders from having to sustain their investments for an unreasonably long period if AltC failed to find a suitable business combination in the timeframe contemplated by the Certificate of Incorporation. We also believe that, given the Company’s expenditure of time, effort and money on finding a business combination and our entry into the Merger Agreement with respect to the Business Combination, circumstances warrant providing public stockholders an opportunity to consider the Business Combination.

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SPECIAL MEETING OF ALTC STOCKHOLDERS

The AltC Special Meeting

We are furnishing this proxy statement to our stockholders as part of the solicitation of proxies by the Board for use at the Special Meeting. This Proxy Statement provides you with information you need to know to be able to vote or instruct your vote to be cast at the Special Meeting.

Date, Time and Place of Special Meeting

The Special Meeting will be held on October 5, 2023, at 11 a.m., Eastern Time, conducted via live webcast at the following address https://www.cstproxy.com/altcacquisitioncorp/2023. You will need the control number that is printed on your proxy card to enter the Special Meeting. AltC recommends that you log in at least 15 minutes before the Special Meeting to ensure you are logged in when the Special Meeting starts. Please note that you will not be able to attend the Special Meeting in person.

Proposals at the Special Meeting

At the Special Meeting, AltC will ask AltC stockholders to vote in favor of the following proposals:

Proposal No. 1 — The “Extension Amendment Proposal” — To amend the Certificate of Incorporation, in the form set forth in Annex A, to extend the date by which AltC has to consummate a business combination from October 12, 2023, to July 12, 2024 (or such earlier date as determined by the Board); and

Voting Power; Record Date

You will be entitled to vote or direct votes to be cast at the Special Meeting if you owned shares of Class A Common Stock or Class B Common Stock at the close of business on September 1, 2023, which is the Record Date for the Special Meeting. You are entitled to one vote for each share of Class A Common Stock or Class B Common Stock that you owned as of the close of business on the Record Date. If your shares are held in “street name” or are in a margin or similar account, you should contact your broker, bank or other nominee to ensure that votes related to the shares you beneficially own are properly counted. On the Record Date, there were 51,450,000 shares of Class A Common Stock outstanding and 12,500,000 shares of Class B Common Stock outstanding. All of the outstanding shares of Class B Common Stock are held by Sponsor.

Sponsor has agreed to vote all of its shares of Common Stock in favor of the Extension Amendment Proposal and the Adjournment Proposal.

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Recommendation of the Board

THE BOARD UNANIMOUSLY (OF THOSE WHO VOTED) RECOMMENDS
THAT YOU VOTE “FOR” EACH OF THESE PROPOSALS

Quorum and Required Vote for Proposals for the Special Meeting

The approval of the Extension Amendment Proposal requires the affirmative vote of the holders of at least 65% of all the outstanding shares of Common Stock as of the Record Date. The presence, in person or by proxy, at the Special Meeting of the holders of shares of outstanding Common Stock representing a majority of the voting power of all issued and outstanding shares of Common Stock entitled to vote as of the Record Date at the Special Meeting shall constitute a quorum for the vote on the Extension Amendment Proposal. Accordingly, an AltC stockholder’s failure to vote by proxy or to vote in person at the Special Meeting will not be counted towards the number of shares of Common Stock required to validly establish a quorum, and if a valid quorum is otherwise established, such failure to vote will have the effect of voting “AGAINST” the Extension Amendment Proposal. Abstentions (but not broker non-votes) will be counted in connection with the determination of whether a valid quorum is established, and will have the effect of voting “AGAINST” the Extension Amendment Proposal.

Approval of the Adjournment Proposal requires the affirmative vote of a majority of the votes cast by the holders of the shares of Common Stock, voting together as a single class, present in person or represented by proxy at the Special Meeting and entitled to vote thereon. The presence, in person or by proxy, at the Special Meeting of the holders of shares of outstanding Common Stock representing a majority of the voting power of all issued and outstanding shares of Common Stock entitled to vote as of the Record Date at the Special Meeting shall constitute a quorum for the vote on the Adjournment Proposal. Accordingly, an AltC stockholder’s failure to vote by proxy or to vote in person at the Special Meeting will not be counted towards the number of shares of Common Stock required to validly establish a quorum, but if a valid quorum is otherwise established, such failure to vote will have no effect on the outcome of any vote on the Adjournment Proposal. Abstentions (but not broker non-votes), while considered present for the purposes of establishing a quorum, will not count as a vote cast at the Special Meeting and will have no effect on the outcome of any vote on the Adjournment Proposal.

It is possible that AltC will not be able to complete its initial business combination on or before the Extended Date if the Extension Amendment Proposal is approved. If AltC fails to complete its initial business combination on or before the Extended Date if the Extension Amendment Proposal is approved, AltC will be required to dissolve and liquidate the Trust Account by returning the then remaining funds in such account to the public stockholders.

No Additional Matters

The Special Meeting has been called only to consider and vote on the approval of the Extension Amendment Proposal and the Adjournment Proposal. Under the Company’s bylaws, other than procedural matters incident to the conduct of the Special Meeting, no other matters may be considered at the Special Meeting if they are not included in this proxy statement, which serves as the notice of the Special Meeting.

If AltC does not implement the Extension, it will not redeem any Public Shares submitted for Redemption in connection with the Special Meeting.

Who Can Answer Your Questions about Voting

If you have any questions about how to vote or direct a vote in respect of your shares of Common Stock, you may call Morrow, our proxy solicitor toll-free at (800) 662-5200 or (203) 658-9400.

Redemption Rights

If the Extension Amendment Proposal is approved, and contingent upon the effectiveness of the implementation of the Extension, the Company will provide public stockholders making the Election the opportunity to receive, at the time the Extension becomes effective, and in exchange for the surrender of their Public Shares, a pro rata portion of the funds available in the Trust Account including any interest earned

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on the funds held in the Trust Account but after Permitted Withdrawals and net of taxes payable. You will be able to redeem your Public Shares in connection with any stockholder vote to approve a proposed initial business combination or if the Company has not consummated an initial business combination by the Extended Date.

You will be entitled to receive cash for any Public Shares to be redeemed in connection with the Extension Amendment Proposal only if you:

(i)

hold Public Shares, and

(ii)

prior to 5:00 p.m., Eastern Time, on October 3, 2023, (a) submit a written request to Continental Stock Transfer & Trust Company (“Continental”) that AltC redeem your Public Shares for cash and (b) deliver your stock certificates (if any) and other redemption forms to Continental, physically or electronically through DWAC.

Holders of Public Shares do not need to affirmatively vote on the Extension Amendment Proposal or be a holder of such Public Shares as of the Record Date to exercise redemption rights. If the Extension Amendment Proposal is not approved, these Public Shares will not be redeemed for cash. If a holder of Public Shares properly demands redemption, delivers his, her or its stock certificates (if any) and other redemption forms to Continental, and the Extension Amendment Proposal is consummated, we will redeem each Public Shares for the Per-Share Redemption Price. It is anticipated that this would amount to approximately $10.33 per share. If a holder of Public Shares exercises his, her or its redemption rights, then such holder will be exchanging his, her or its Public Shares for cash and will no longer own such Public Shares.

Holders may demand redemption by delivering their stock certificates (if any) and other redemption forms, either physically or electronically using DTC’s DWAC System, to the Company’s transfer agent prior to the vote at the Special Meeting. If you hold the shares in “street name,” you will have to coordinate with your broker to have your shares certificated or delivered electronically. Certificates that have not been tendered (either physically or electronically) in accordance with these procedures will not be redeemed for cash. There is a nominal cost associated with this tendering process and the act of certificating the shares or delivering them through the DWAC system. The transfer agent will typically charge the tendering broker $100 and it would be up to the broker whether or not to pass this cost on to the redeeming stockholder.

The Company’s transfer agent can be contacted at the following address:

Continental Stock Transfer & Trust Company
1 State Street — 30th Floor
New York, New York 10004
Attn: SPAC Administration Team
Email: spacredemptions@continentalstock.com

Furthermore, if a holder of a Public Share delivered its certificate in connection with an election of its redemption and subsequently decides prior to the applicable date not to elect to exercise such rights, it may simply request that the transfer agent return the certificate (physically or electronically).

The closing price of our Public Shares on September 1, 2023, the Record Date, was $10.34 per share. The cash held in the Trust Account on such date was approximately $516,729,800 (including interest not previously released to AltC but net of taxes payable) (or approximately $10.33 per Public Share). Prior to exercising redemption rights, stockholders should verify the market price of Public Shares as they may receive higher proceeds from the sale of their Public Shares in the public market than from exercising their redemption rights if the market price per share is higher than the redemption price. The Company cannot assure its stockholders that they will be able to sell their Public Shares in the open market, even if the market price per share is higher than the redemption price stated above, as there may not be sufficient liquidity in its securities when its stockholders wish to sell their shares.

If you elect to redeem your Public Shares, you will have no right to participate in, or have any interest in, the future growth of AltC, if any. You will be entitled to receive cash for your Public Shares only if you properly and timely demand redemption.

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If AltC does not consummate an initial business combination on or before the Termination Date, and the Extension Amendment Proposal is not approved, AltC will be required to dissolve and liquidate the Trust Account by returning the then remaining funds in such account to the public stockholders.

Your right to redeem your Public Shares in connection with the Special Meeting relating to the Extension Amendment Proposal does not affect the right of AltC stockholders to elect to redeem their Public Shares in connection with the Business Combination, which is a separate and additional redemption right available to AltC stockholders.

If a holder of Public Shares exercises his, her or its redemption rights, then he, she or it will be exchanging its Public Shares for cash and will no longer own those shares.

TO EXERCISE YOUR REDEMPTION RIGHTS, YOU MUST ELECT TO HAVE ALTC REDEEM YOUR SHARES FOR A PRO RATA PORTION OF THE FUNDS HELD IN THE TRUST ACCOUNT AND TENDER YOUR SHARES TO ALTC’S TRANSFER AGENT AT LEAST TWO BUSINESS DAYS PRIOR TO THE VOTE AT THE SPECIAL MEETING. YOU MAY TENDER YOUR SHARES BY EITHER DELIVERING YOUR SHARE CERTIFICATE TO THE TRANSFER AGENT OR BY DELIVERING YOUR SHARES ELECTRONICALLY USING THE DEPOSITORY TRUST COMPANY’S DWAC (DEPOSIT WITHDRAWAL AT CUSTODIAN) SYSTEM. IF THE EXTENSION IS NOT APPROVED, THEN THESE SHARES WILL NOT BE REDEEMED FOR CASH. IF YOU HOLD THE SHARES IN STREET NAME, YOU WILL NEED TO INSTRUCT THE ACCOUNT EXECUTIVE AT YOUR BANK OR BROKER TO WITHDRAW THE SHARES FROM YOUR ACCOUNT IN ORDER TO EXERCISE YOUR REDEMPTION RIGHTS.

In connection with tendering your shares for redemption, prior to 5:00 p.m. Eastern Time on October 3, 2023 (two business days before the Special Meeting), you must elect either to physically tender your stock certificates to Continental Stock Transfer & Trust Company at 1 State Street, 30th Floor, New York, New York 10004, Attn: SPAC Administration Team, spacredemptions@continentalstock.com, or to deliver your Public Shares to Continental electronically using DTC’s DWAC system, which election would likely be determined based on the manner in which you hold your shares. The requirement for physical or electronic delivery prior to 5:00 p.m. Eastern Time on October 3, 2023 (two business days before the Special Meeting), ensures that a redeeming holder’s election is irrevocable once the Extension Amendment Proposal is approved. In furtherance of such irrevocable election, stockholders making the election will not be able to tender their shares after the vote at the Special Meeting.

Through the DWAC system, this electronic delivery process can be accomplished by the stockholders, whether or not it is a record holder or its shares are held in “street name,” by contacting Continental Stock Transfer & Trust Company or its broker and requesting delivery of its shares through the DWAC system. Delivering shares physically may take significantly longer. In order to obtain a physical share certificate, a stockholder’s broker and/or clearing broker, DTC, and the Company’s transfer agent will need to act together to facilitate this request. There is a nominal cost associated with the above-referenced tendering process and the act of certificating the shares or delivering them through the DWAC system. Continental Stock Transfer & Trust Company will typically charge the tendering broker $100 and the broker would determine whether or not to pass this cost on to the redeeming holder. It is the Company’s understanding that stockholders should generally allot at least two weeks to obtain physical certificates from the transfer agent. The Company does not have any control over this process or over the brokers or DTC, and it may take longer than two weeks to obtain a physical share certificate. Such stockholders will have less time to make their investment decision than those stockholders that deliver their shares through the DWAC system. Stockholders who request physical stock certificates and wish to redeem may be unable to meet the deadline for tendering their shares before exercising their redemption rights and thus will be unable to redeem their shares.

Certificates that have not been tendered in accordance with these procedures prior to 5:00 p.m. Eastern Time on Ocotber 3, 2023 (two business days before the Special Meeting), will not be redeemed for cash held in the Trust Account on the redemption date. In the event that a public stockholder tenders its shares and decides prior to the vote at the Special Meeting that it does not want to redeem its shares, the stockholder may withdraw the tender. If you delivered your shares for redemption to our transfer agent and decide prior to the vote at the Special Meeting not to redeem your Public Shares, you may request that our transfer agent

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return the shares (physically or electronically). You may make such request by contacting our transfer agent at the address listed above. In the event that a public stockholder tenders shares and the Extension Amendment Proposal is not approved, these shares will not be redeemed and the physical certificates representing these shares will be returned to the stockholder promptly following the determination that the Extension Amendment Proposal will not be approved. If you exercise your redemption rights, you will be exchanging your Public Shares for cash and will no longer own the shares. You will be entitled to receive cash for these shares only if you properly demand redemption and tender your stock certificate(s) to the Company’s transfer agent prior to 5:00 p.m. Eastern Time on October 3, 2023 (two business days before the Special Meeting). The Company anticipates that a public stockholder who tenders shares for redemption in connection with the vote to approve the Extension Amendment Proposal would receive payment of the redemption price for such shares soon after the completion of the Extension. The transfer agent will hold the certificates of public stockholders that make the election until such shares are redeemed for cash or returned to such stockholders. If the Extension Amendment Proposal is not approved or is abandoned, these shares will be returned promptly following the Special Meeting as described above.

Redemption Withdrawal Procedures

The Board may elect to abandon the Extension Amendment Proposal at any time and for any reason without any further action by our stockholders.

Immediately following the Redemption Deadline to make an Election (which is 5:00 P.M. Eastern Time on October 3, 2023, the date that is two business days prior to the scheduled vote at the Special Meeting), a public stockholder that desires to withdraw its Election may effectuate an Election Reversal. In order to effectuate an Election Reversal, including one for which a commitment has previously been made on a reversal commitment form, you must request that transfer agent return the shares (physically or electronically) as soon as possible after the Redemption Deadline. Such written request shall include your legal name, phone number and address of the beneficial owner of the shares for which reversal is requested. If you hold the shares in street name, you will need to instruct the account executive at your bank or broker to request reversal of the tender from the transfer agent.

TO MAKE AN ELECTION REVERSAL WITH RESPECT TO YOUR PUBLIC SHARES, YOU MUST SUBMIT A WRITTEN REQUEST TO THE TRANSFER AGENT, AFTER 5:00 P.M. EASTERN TIME ON OCTOBER 3, 2023, THE DATE THAT IS TWO BUSINESS DAYS PRIOR TO THE SCHEDULED VOTE AT THE SPECIAL MEETING, AND PRIOR TO THE SCHEDULED VOTE AT THE SPECIAL MEETING, THAT THE TENDER OF YOUR PUBLIC SHARES BE REVERSED, INCLUDING THE LEGAL NAME, PHONE NUMBER, AND ADDRESS OF THE BENEFICIAL OWNER OF THE SHARES FOR WHICH REVERSAL IS REQUESTED AND THE NUMBER OR PERCENTAGE OF SHARES FOR WHICH REVERSAL IS REQUESTED. IF YOU HOLD THE SHARES IN STREET NAME, YOU WILL NEED TO INSTRUCT THE ACCOUNT EXECUTIVE AT YOUR BANK OR BROKER TO REQUEST REVERSAL OF THE ELECTION TO REDEEM FROM THE TRANSFER AGENT.

Notwithstanding stockholder approval of the Extension Amendment Proposal or the number of Elections (taking into account any Election Reversals) by our public stockholders, the Board will retain the right to abandon the Extension Amendment Proposal or postpone or cancel the Special Meeting at any time and for any reason without any further action by our stockholders.

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Appraisal or Dissenters’ Rights

No appraisal or dissenters’ rights are available to holders of shares of Common Stock in connection with the Extension Amendment Proposal.

Solicitation of Proxies

AltC will pay the cost of soliciting proxies for the Special Meeting. AltC has engaged Morrow to assist in the solicitation of proxies for the Special Meeting. AltC has agreed to pay Morrow a fee of up to $30,000 in connection with the Extension Amendment. AltC will reimburse Morrow for reasonable and customary documented out-of-pocket expenses and will indemnify Morrow and its directors, officers, employees and agents against certain claims, liabilities, losses, damages and expenses. AltC also will reimburse banks, brokers and other custodians, nominees and fiduciaries representing beneficial owners of Public Shares for their expenses in forwarding soliciting materials to beneficial owners Public Shares and in obtaining voting instructions from those owners. AltC’s directors, officers and employees may also solicit proxies by telephone, by facsimile, by mail, on the Internet or in person. They will not be paid any additional amounts for soliciting proxies.

Interests of Sponsor and AltC’s Directors and Officers

When you consider the recommendation of the Board, AltC stockholders should be aware that aside from their interests as stockholders, Sponsor and certain members of the Board and officers have interests that are different from, or in addition to, those of other stockholders generally. The Board was aware of and considered these interests, among other matters, in recommending to AltC stockholders that they approve the Extension Amendment Proposal. AltC stockholders should take these interests into account in deciding whether to approve the Extension Amendment Proposal:

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in order to fund working capital deficiencies or finance transaction costs in connection with an initial business combination, Sponsor, the Company’s directors and officers, or their affiliates may, but are not obligated to, loan us funds as may be required. If we complete a business combination, we would repay such loaned amounts out of the Trust Account. In the event that a business combination does not close, we may use a portion of the working capital held outside the Trust Account to repay such loaned amounts but no proceeds from our Trust Account would be used for such repayment. Up to $1,500,000 of such loans may be convertible into shares of the post-business combination entity at a price of $10.00 per share (the “Extension Working Capital Loan”);

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the beneficial ownership of Sponsor and certain members of the Board and officers of an aggregate of (i) 12,500,000 shares of Class B Common Stock, which shares were acquired for an aggregate investment of $25,000 at the time of the IPO and (ii) 1,450,000 shares of Class A Common Stock, which shares were purchased for $14,500,000 concurrently with the IPO through a private placement, all of which shares described in the foregoing would become worthless if AltC does not complete a business combination by October 12, 2023 (or July 12, 2024, if the Extension Amendment Proposal is approved (or such earlier date as determined by the Board)), as such stockholders have waived any redemption right with respect to these shares. Such shares have an aggregate market value of approximately $144,243,000, based on the closing price of shares of Class A Common Stock of $10.34 per share on September 1, 2023, the Record Date. Because the shares of Class B Common Stock were purchased for a nominal amount, Sponsor could achieve a significant positive return even if the trading price of shares of AltC following the closing of the Business Combination declines significantly. In addition, after giving effect to the possible issuance of a maximum of 150,000 additional shares of Common Stock that may be issued pursuant to the Extension Working Capital Loan, Sponsor would own up to an aggregate of 14,100,000 shares of Common Stock following the consummation of the Business Combination. Such shares of Common Stock have an aggregate market value of approximately $145,794,000, based on the closing price per share of the Public Shares of $10.34 on September 1, 2023, the Record Date. Each of Michael Klein, Sam Altman, Frances Frei, Allison Green, Peter Lattman and John L. Thornton, all of whom are directors of AltC, has a direct or indirect economic interest (or may have a deemed economic interest) in the founder shares and Private Placement Shares purchased by Sponsor, but does not beneficially own any of the Common Stock;

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pursuant to the terms of the Sponsor Agreement, Sponsor and the directors and officers of AltC agreed, among other things, (i) to vote any shares of AltC’s securities held by such party in favor of the Extension Amendment Proposal, the Adjournment Proposal and the proposals to be voted on at the Business Combination Special Meeting, (ii) not to redeem any shares of Class A Common Stock or Class B Common Stock and (iii) not to transfer:

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40% of their AltC shares for a period of 12 months after the closing of the Business Combination, unless the closing share price of Class A Common Stock equals or exceeds $12.00 per share for 20 trading days within any 60 consecutive trading day period commencing after the date on which the closing of the Business Combination occurs;

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30% of their AltC shares for a period of 24 months after the closing of the Business Combination, unless the closing share price of Class A Common Stock equals or exceeds $14.00 per share for 20 trading days within any 60 consecutive trading day period commencing after the date on which the closing of the Business Combination occurs; and

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30% of their AltC shares for a period of 36 months after the closing of the Business Combination, unless the closing share price of Class A Common Stock equals or exceeds $16.00 per share for 20 trading days within any 60 consecutive trading day period commencing after the date on which the closing of the Business Combination occurs;

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if AltC is unable to complete its initial business combination by the Termination Date, the Sponsor will be liable under certain circumstances to ensure that the proceeds in the Trust Account are not reduced by the claims of target businesses or claims of vendors or other entities that are owed money by AltC for services rendered or contracted for or products sold to AltC. If AltC consummates a business combination, on the other hand, AltC will be liable for all such claims;

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after our initial business combination, members of our management team who remain with us, if any, may be paid consulting, management or other fees from the combined company with any and all amounts being fully disclosed to our stockholders, to the extent then known, in the tender offer or proxy solicitation materials, as applicable, furnished to our stockholders. It is unlikely the amount of such compensation will be known at the time of distribution of such tender offer materials or at the time of a stockholder meeting held to consider our initial business combination, as applicable, as it will be up to the directors of the post-combination business to determine executive officer and director compensation;

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in connection with the Business Combination, Sponsor and the officers and directors of AltC have each entered into the Sponsor Agreement, pursuant to which they have: (a) acknowledged that such person has no right, title, interest or claim of any kind in or to any monies held in the Trust Account as a result of any liquidation of the Company with respect to the shares of Class B Common Stock held by such person and (b) waived, with respect to any shares of Common A Common Stock held by the such person, if any, any redemption rights such person may have in connection with the consummation of an initial business combination;

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in March 2021, Sponsor agreed to loan AltC up to $600,000 to cover expenses related to the IPO pursuant to a promissory note. The loan was non-interest bearing, unsecured and due on the earlier of December 31, 2021 or the closing of the IPO. AltC borrowed $500,000 under this promissory note and repaid the full outstanding balance of the promissory note on July 12, 2021;

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AltC entered into an Administrative Services Agreement pursuant to which AltC will pay an affiliate of our Sponsor a total of $30,000 per month for office space and administrative and support services. Upon completion of an initial business combination or dissolution of AltC, AltC will cease paying these monthly fees. Accordingly, if the Extension is approved and implemented, subject to satisfaction of the conditions to closing in the Merger Agreement (including, without limitation, receipt of the approval of the stockholders of AltC at the Business Combination Special Meeting), AltC intends to complete the Business Combination as soon as practicable and in any event on or before the Extended Date. In event the consummation of AltC’s initial business combination closes on the Extended Date, an affiliate of our Sponsor will be paid a total of $810,000 ($30,000 per month) for office space, administrative and support services and will be entitled to be reimbursed for any out-of-pocket expenses. As of the Record Date, AltC has incurred $773,255 in fees;

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the continued indemnification of current directors and officers of AltC and the continuation of directors’ and officers’ liability insurance after the Business Combination;

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the fact that Sponsor, our officers and directors or any of their respective affiliates will be reimbursed for any reasonable out-of-pocket expenses incurred in connection with activities on our behalf, such as identifying potential target businesses and performing due diligence on suitable business combinations. There is no cap or ceiling on the reimbursement of out-of-pocket expenses incurred by such persons in connection with activities on our behalf. As of the Record Date, Sponsor and its affiliates have not incurred any unpaid reimbursable expenses; and

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the fact that Sponsor, our officers and directors will lose their entire investment in us if an initial business combination is not completed.

Additionally, if the Extension Amendment Proposal is approved and AltC consummates an initial business combination, the officers and directors may have additional interests that will be described in the Business Combination Registration Statement.

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PROPOSAL NO. 1 — THE EXTENSION AMENDMENT PROPOSAL

Overview

AltC is proposing to amend the Certificate of Incorporation to extend the date by which AltC has to consummate a business combination from the Termination Date to the Extended Date. The purpose of the Extension Amendment Proposal is to give AltC additional time to complete the Business Combination. A copy of the proposed amendment to the Certificate of Incorporation is attached to this Proxy Statement as Annex A.

The Business Combination qualifies as a “business combination” under the Certificate of Incorporation.

The Board believes that it is in the best interests of AltC stockholders that the Extension be implemented so that AltC will have additional time to complete the Business Combination. Without the Extension, AltC would not be able to complete the Business Combination on or before the Termination Date. If that were to occur, AltC would be precluded from completing the Business Combination and would be forced to liquidate even if AltC stockholders are otherwise in favor of consummating the Business Combination.

As contemplated by the Certificate of Incorporation, the holders of Public Shares may elect to redeem all or a portion of their Public Shares in exchange for their pro rata portion of the funds held in the Trust Account if the Extension is implemented. If the Extension Amendment Proposal is approved by the requisite vote of stockholders, the remaining holders of Public Shares will retain their right to redeem their Public Shares when the Business Combination is submitted to the stockholders, subject to any limitations set forth in the Certificate of Incorporation as amended by the Extension Amendment. In addition, public stockholders who do not make the Election would be entitled to have their Public Shares redeemed for cash if AltC has not completed a business combination by the Extended Date.

On the Record Date, the redemption price per share was approximately $10.33, based on the aggregate amount on deposit in the Trust Account of approximately $516,729,800 as of the Record Date (including interest not previously released to AltC but net of taxes payable), divided by the total number of then outstanding Public Shares. The closing price of the shares of Class A Common Stock on the NYSE on the Record Date was $10.34 per share. Accordingly, if the market price of the shares of Class A Common Stock were to remain the same until the date of the Special Meeting, exercising redemption rights would result in a public stockholder receiving approximately $0.01 less per share than if the stock was sold in the open market. AltC cannot assure stockholders that they will be able to sell their Public Shares in the open market, even if the market price per share is higher than the redemption price stated above, as there may not be sufficient liquidity in its securities when such stockholders wish to sell their shares. AltC believes that such redemption right enables its public stockholders to determine whether or not to sustain their investments for an additional period if AltC does not complete the Business Combination on or before the Termination Date.

Reasons for the Extension Amendment Proposal

The Certificate of Incorporation provides that AltC currently has until October 12, 2023, to complete an initial business combination. The purpose of the Extension Amendment is to allow AltC more time to complete its initial business combination.

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As previously announced, we entered into the Merger Agreement on July 11, 2023. Pursuant to the Merger Agreement, and subject to its terms and conditions, the parties agreed to effect the Business Combination. The Certificate of Incorporation provides that AltC currently has until October 12, 2023, to complete its initial business combination. The Board currently believes that there will not be sufficient time before October 12, 2023, to complete the Business Combination. Accordingly, the Board believes that in order to be able to complete the Business Combination, we will need to obtain the Extension. Without the Extension, we believe that we will not be able to complete the Business Combination on or before October 12, 2023. If that were to occur, we would be precluded from completing the Business Combination and would be forced to liquidate even if our stockholders are otherwise in favor of consummating the Business Combination. For more information about the Business Combination, see our Current Report on Form 8-K filed with the SEC on July 11, 2023, and our other filings with the SEC.

The Company’s IPO prospectus and the Certificate of Incorporation provide that the affirmative vote of the holders of at least 65% of all outstanding shares of Common Stock is required to extend our corporate existence, except in connection with, and effective upon, consummation of a business combination. Additionally, our IPO prospectus and the Certificate of Incorporation provide for all public stockholders to have an opportunity to redeem their Public Shares in the case our corporate existence is extended as described above. Because we continue to believe that pursuing the Business Combination is in the best interests of our stockholders, and because we will not be able to conclude the Business Combination within the permitted time period, the Board has determined to seek stockholder approval to extend the date by which we have to complete a business combination beyond October 12, 2023, to the Extended Date. We intend to hold the Business Combination Special Meeting prior to the Extended Date in order to seek stockholder approval of the Business Combination. We will not proceed with the Extension if the number of redemptions of our Public Shares (after taking into account any Election Reversals) causes AltC to have less than $5,000,001 of net tangible assets following approval of the Extension Amendment Proposal. The Merger Agreement provides that the consummation of the Business Combination is conditioned upon, among other things, AltC having at least $5,000,001 of net tangible assets as of the closing of the Business Combination. Additionally, the obligations of Oklo to complete the Business Combination are conditioned upon, among other things, the amount of cash available in the Trust Account (including, the net proceeds of any incremental financing raised by AltC or Oklo in connection with the transactions contemplated by the Merger Agreement) being at least $250,000,000, after reduction for redemptions made in connection with the Business Combination Special Meeting and any excise tax payable by AltC, but before giving effect to the payment of transaction expenses.

If the Extension Amendment Proposal is Not Approved

Stockholder approval of the Extension Amendment is required for the implementation of the Board’s plan to extend the date by which we must consummate our initial business combination. Therefore, the Board will abandon and not implement the Extension Amendment unless our stockholders approve the Extension Amendment Proposal.

If the Extension Amendment Proposal is not approved and the Business Combination is not completed on or before the Termination Date, AltC will: (i) cease all operations except for the purpose of winding up, (ii) as promptly as reasonably possible but not more than ten business days thereafter subject to lawfully available funds therefor, redeem 100% of the Public Shares in consideration of a per share price, payable in cash, equal to the quotient obtained by dividing (A) the aggregate amount then on deposit in the Trust Account, including interest (net of amounts withdrawn as Permitted Withdrawals and less up to $100,000 of such net interest to pay dissolution expenses), by (B) the total number of then outstanding Public Shares, which redemption will completely extinguish rights of the holders of Public Shares (including the right to receive further liquidating distributions, if any), subject to applicable law, and (iii) as promptly as reasonably

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possible following such redemption, subject to the approval of the remaining stockholders and the Board in accordance with applicable law, dissolve and liquidate, subject in each case to AltC’s obligations under the DGCL to provide for claims of creditors and other requirements of applicable law.

Sponsor and the officers and directors of AltC have each acknowledged they have no right to any liquidating distributions with respect to the 13,950,000 shares of Common Stock held by them on the Record Date. AltC will pay any costs of liquidation from its remaining assets outside of the Trust Account.

If the Extension Amendment Proposal is Approved

If the Extension Amendment Proposal is approved, AltC intends to file an amendment to the Certificate of Incorporation with Delaware in the form of Annex A hereto to extend the time it has to complete a business combination until the Extended Date. AltC will then continue to attempt to consummate a business combination until the Extended Date. AltC will remain a reporting company under the Exchange Act and its Common Stock is expected to remain publicly traded during this time.

If the Extension Amendment Proposal is approved, and the Extension is implemented, the removal of the Withdrawal Amount from the Trust Account in connection with the Election will reduce the amount held in the Trust Account. The Company cannot predict the amount that will remain in the Trust Account if the Extension Amendment Proposal is approved, and the amount remaining in the Trust Account may be only a small fraction of the amount currently held in the Trust Account.

Certain Material U.S. Federal Income Tax Consequences

The following discussion is a general summary of certain material U.S. federal income tax consequences to AltC’s stockholders with respect to the exercise of redemption rights in connection with the approval of the Extension Amendment. This discussion assumes that holders currently hold AltC securities as capital assets within the meaning of Section 1221 of the Internal Revenue Code of 1986, as amended (the “Code”).

This discussion does not describe all of the U.S. federal income tax consequences that may be relevant to you in light of your particular circumstances, including the alternative minimum tax, the Medicare tax on certain investment income and except as otherwise discussed below, the special tax rules that may apply to certain types of investors, such as:

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banks or financial institutions;

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insurance companies;

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brokers, dealers or traders in securities, commodities or currencies;

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traders that elect to use a mark-to-market method of accounting;

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persons holding the securities as part of a “straddle,” hedge, integrated transaction or similar transaction;

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U.S. Holders (as defined below) whose functional currency is not the U.S. dollar;

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U.S. expatriates or former long-term residents of the United States;

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partnerships or other pass-through entities for U.S. federal income tax purposes and any beneficial owners of such entities;

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S corporations;

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regulated investment companies;

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real estate investment trusts;

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grantor trusts;

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persons whose Public Shares are subject to a liability;

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persons holding founder shares;

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persons subject to the applicable financial statement accounting rules under Section 451(b) of the Code;

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Non-U.S. Holders (as defined below); and

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tax-exempt entities.

If a partnership, or another entity or arrangement treated as a partnership for U.S. federal income tax purposes, holds Public Shares, the U.S. federal income tax treatment of its partners or members generally will depend on the status of the partner and the activities of the partnership or other pass-through entity. Accordingly, partnerships or other entities treated as partnership for U.S. federal income tax purposes that hold Public Shares, and partners or members in those entities, are urged to consult their tax advisors regarding the specific U.S. federal income tax consequences to them.

This discussion is based on the Code, and administrative pronouncements, judicial decisions and final, temporary and proposed Treasury regulations as of the date hereof, all of which are subject to differing interpretations or change, possibly on a retroactive basis. This discussion does not address any aspect of state, local or non-U.S. taxation, or any U.S. federal taxes other than income tax (such as gift and estate taxes).

THE FOLLOWING DISCUSSION IS FOR GENERAL INFORMATIONAL PURPOSES ONLY AND SHOULD NOT BE CONSTRUED AS TAX ADVICE. YOU ARE URGED TO CONSULT YOUR TAX ADVISOR WITH RESPECT TO THE SPECIFIC TAX CONSEQUENCES TO YOU OF MAKING OR NOT MAKING THE ELECTION TO REDEEM YOUR PUBLIC SHARES, INCLUDING THE EFFECTS OF U.S. FEDERAL, STATE, LOCAL AND NON-U.S. TAX RULES AND POSSIBLE CHANGES IN LAWS THAT MAY AFFECT THE TAX CONSEQUENCES DESCRIBED IN THIS PROXY STATEMENT.

U.S. Federal Income Tax Consequences to Non-Redeeming Stockholders

A stockholder who does not elect to redeem its Public Shares will continue to own its Public Shares and will not recognize any income, gain or loss for U.S. federal income tax purposes by reason of the Extension.

U.S. Federal Income Tax Consequences of the Redemption to U.S. Holders of Public Shares

For purposes of this discussion, a U.S. Holder is a beneficial owner of Public Shares who or that is, for U.S. federal income tax purposes:

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an individual who is a citizen or resident of the United States;

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a corporation (or other entity taxable as a corporation for U.S. federal income tax purposes) organized in or under the laws of the United States, any state thereof or the District of Columbia;

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an estate the income of which is subject to U.S. federal income taxation regardless of its source; or

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a trust (i) the administration of which is subject to the primary supervision of a court in the United States and for which one or more U.S. persons have the authority to control all substantial decisions or (ii) that has an election in effect under applicable income tax regulations to be treated as a United States person for U.S. federal income tax purposes.

A Non-U.S. Holder is a beneficial owner of Public Shares (other than a partnership or other entity or arrangement treated as a partnership for U.S. federal income tax purposes) that is not a U.S. Holder.

This section summarizes the expected U.S. federal income tax consequences of the redemption of Public Shares for U.S. Holders of Public Shares.

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In the event that you elect to have your Public Shares redeemed, the treatment of the transaction for U.S. federal income tax purposes will depend on whether the redemption qualifies as a sale or exchange of the Public Shares under Section 302 of the Code.

If the redemption qualifies as a sale or exchange of the Public Shares, you generally will recognize capital gain or loss in an amount equal to the difference between (i) the amount of cash received in respect of the Public Shares and (ii) your adjusted tax basis in your Public Shares. Your adjusted tax basis in the Public Shares generally should equal your acquisition cost for those shares. The price allocated to the one Public Share generally should be the holder’s tax basis in such Public Share. The foregoing treatment of the Public Shares, including the holder’s allocation of the tax basis, is not binding on the Internal Revenue Service (the “IRS”), or the courts. Accordingly, each holder is urged to consult its tax advisors regarding the tax consequences of the exercise of redemption rights.

Any such capital gain or loss generally will be long-term capital gain or loss if your holding period for the Public Shares so disposed of exceeds one year at the time of the disposition. It is unclear, however, whether the redemption rights with respect to the Public Shares may have suspended the running of the applicable holding period for this purpose. Long-term capital gains recognized by you if you are a non-corporate U.S. Holder may be eligible to be taxed at reduced rates. The deductibility of capital losses is subject to certain limitations.

If the redemption does not qualify as a sale or exchange of Public Shares, you will be treated as receiving a cash distribution from AltC. Such distribution generally will constitute a dividend for U.S. federal income tax purposes to the extent paid from AltC’s current or accumulated earnings and profits, as determined under U.S. federal income tax principles. Distributions in excess of current and accumulated earnings and profits will constitute a return of capital that will be applied against and reduce (but not below zero) your adjusted tax basis in your Public Shares. Any remaining excess will be treated as gain realized on the sale or other disposition of your Public Shares and will be taxed in the manner described in the preceding paragraphs. If you are taxable as a corporation for U.S. federal income tax purposes, the portion of any redemption payment that AltC pays to you that is treated as a dividend generally will qualify for the dividends received deduction if the requisite holding period is satisfied. If you are a non-corporate U.S. Holder, with certain exceptions (including, but not limited to, if you elect to treat such dividends as investment income for purposes of investment interest deduction limitations) and provided certain holding period requirements are met, any portion of any redemption payment that AltC pays to you that is treated as a dividend generally will constitute “qualified dividends” that may be subject to tax at the maximum tax rate applicable to long-term capital gains. It is unclear whether the redemption rights with respect to the Public Shares would prevent you from satisfying the applicable holding period requirements with respect to the dividends received deduction or the preferential tax rate on qualified dividend income, as the case may be, and, as such, each holder is urged to consult its own tax advisor.

Whether a redemption qualifies for sale or exchange treatment will depend largely on the total number of shares of Public Shares treated as held by you relative to all of AltC’s shares outstanding both before and after the redemption. The redemption of Public Shares generally will be treated as a sale or exchange by you of your Public Shares (rather than as a corporate distribution) if the redemption (i) is “substantially disproportionate” with respect to you, (ii) results in a “complete termination” of your interest in AltC or (iii) is “not essentially equivalent to a dividend” with respect to you. These tests are explained more fully below.

In determining whether any of the foregoing tests are satisfied, you would take into account not only stock actually owned by you, but also shares of AltC stock that you constructively own. You may constructively own, in addition to stock owned directly, stock owned by certain related individuals and entities in which you have an interest or that have an interest in you, as well as any stock you have a right to acquire by exercise of an option. In order to meet the substantially disproportionate test, the percentage of AltC’s outstanding voting stock actually and constructively owned by you immediately following the redemption of Public Shares must, among other requirements, be less than 80% of the percentage of its outstanding voting stock actually and constructively owned by you immediately before the redemption. There will be a complete termination of your interest if either (i) all of the shares of AltC’s stock actually and constructively owned by you are redeemed or (ii) all of the shares of AltC’s stock actually owned by you are redeemed and you are eligible to waive, and effectively waive in accordance with specific rules, the attribution of stock owned by certain family members and you do not constructively own any other Public Shares. The redemption of the

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Public Shares will not be essentially equivalent to a dividend if the redemption results in a “meaningful reduction” of your proportionate interest in AltC. Whether the redemption will result in a meaningful reduction in your proportionate interest in AltC will depend on your particular facts and circumstances. However, the IRS has indicated in a published ruling that even a small reduction in the proportionate interest of a small minority stockholder in a publicly held corporation who exercises no control over corporate affairs may constitute such a “meaningful reduction.” You should consult your tax advisor as to the tax consequences of a redemption.

If none of the foregoing tests is satisfied, then the redemption will not be treated as a sale or exchange, but will be treated as a distribution to you in respect of your Public Shares and you will be subject to the tax consequences described above. If the amount of the distribution you receive does not exceed your adjusted tax basis in your redeemed Public Shares, any of your remaining tax basis in the redeemed Public Shares will be added to your adjusted tax basis in any of your remaining Public Shares, or, if you have none, possibly, other stock constructively owned by you.

If you are a U.S. Holder who actually or constructively owns five percent or more of AltC’s stock (by vote or value) before redemption, you may be subject to special reporting requirements with respect to a redemption of Public Shares, and you should consult your tax advisor with respect to your reporting requirements.

Holders who hold different blocks of Public Shares (generally, Public Shares purchased or acquired on different dates or at different prices) should consult their tax advisors to determine how the above rules apply to them.

Medicare Tax

Certain U.S. Holders who are individuals, estates or trusts and whose income exceeds certain thresholds will be required to pay a 3.8% Medicare tax on dividends and other income, including capital gain from the sale or disposition of Public Shares.

Information Reporting and Backup Withholding

AltC or its paying agent must report annually to U.S. Holders and the IRS amounts paid to such holders on or with respect to Public Shares during each calendar year, the amount of proceeds from the sale of Public Shares, and the amount of tax, if any, withheld from such payments. A U.S. Holder will be subject to backup withholding on dividends paid on Public Shares and proceeds from the sale or exchange of Public Shares at the applicable rate if the U.S. Holder is not otherwise exempt and (i) the holder fails to provide AltC or its paying agent with a correct taxpayer identification number, (ii) AltC or its paying agent is notified by the IRS that the holder provided an incorrect taxpayer identification number, (iii) AltC or its paying agent is notified by the IRS that the holder failed to properly report payments of interest or dividends or (iv) the holder fails to certify under penalty of perjury that it has provided a correct taxpayer identification number and has not been notified by the IRS that it is subject to backup withholding. A U.S. Holder generally may establish that it is exempt from or otherwise not subject to backup withholding by providing a properly completed IRS Form W-9 to AltC or its paying agent.

Backup withholding is not an additional tax. Any amounts withheld under the backup withholding rules will be allowed as a refund or a credit against your U.S. federal income tax liability, provided that the required information is timely furnished to the IRS.

U.S. Federal Income Tax Consequences of the Redemption to Non-U.S. Holders of Public Shares

General

This section summarizes the expected U.S. federal income tax consequences of the exercise of redemption rights to Non-U.S. Holders of Public Shares. For purposes of the below discussion, if you elect to have your Public Shares redeemed, the characterization for U.S. federal income tax purposes of the redemption of your Public Shares generally will correspond to the U.S. federal income tax characterization

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that would be applicable to such a redemption by a U.S. Holder of Public Shares, as described under “U.S. Federal Income Tax Consequences of the Redemption to U.S. Holders of Public Shares” above.

Taxable Sales or Exchanges

If you are a Non-U.S. Holder who elects to have Public Shares redeemed and the redemption is treated as a sale or exchange of your Public Shares for U.S. federal income tax purposes, you will not be subject to U.S. federal income tax on any gain or loss on such event (which generally would be calculated in the same manner as if you were a U.S. Holder) unless either (i) the gain is effectively connected with the conduct of a trade or business by you within the United States (and, under certain income tax treaties, is attributable to a United States permanent establishment or fixed base maintained by you), (ii) you are an individual present in the United States for 183 days or more in the taxable year of disposition and certain other conditions are met or (iii) AltC is or has been a “United States real property holding corporation” for U.S. federal income tax purposes at any time during the shorter of the five-year period ending on the date of disposition or the period that you held Public Shares and, in the case where Public Shares are regularly traded on an established securities market, you have owned, directly or constructively, more than 5% of the Public Shares, at any time within the shorter of the five-year period preceding the disposition or your holding period for the Public Shares.

Unless an applicable treaty provides otherwise, gain described in clause (i) immediately above will be subject to tax at generally applicable U.S. federal income tax rates as if you were a U.S. resident. Any gain described in clause (i) immediately above if you are a corporation may also be subject to an additional “branch profits tax” at a 30% rate (or lower treaty rate). If you are an individual Non-U.S. Holder described in clause (ii) immediately above, you generally will be subject to a flat 30% U.S. federal income tax on the gain derived from the sale, which may be offset by U.S. source capital losses. If you are eligible for the benefits of an income tax treaty between the United States and your country of residence, any gain described in clause (ii) immediately above will be subject to U.S. federal income tax in the manner specified by the income tax treaty and generally will only be subject to such tax if such gain is attributable to a permanent establishment maintained by you in the United States. To claim the benefit of any applicable income tax treaty, you must properly submit an applicable IRS Form W-8. You should consult your tax advisor regarding the potential application of income tax treaties and your eligibility for income tax treaty benefits.

In the case of clause (iii) two paragraphs above, AltC would be classified as a United States real property holding corporation if the fair market value of AltC’s “United States real property interests” equal or exceed 50 percent of the sum of the fair market value of AltC’s worldwide real property interests plus AltC’s other assets used or held for use in a trade or business, as determined for U.S. federal income tax purposes. As AltC has generally only held cash, cash equivalents and government securities since its inception, AltC does not believe that it is or has ever been a United States real property holding corporation. Further, so long as the Public Shares are considered to be regularly traded at any time during the calendar year, a Non-U.S. Holder generally will not be subject to tax on any gain recognized on the sale or exchange of Public Shares, unless the Non-U.S. Holder owned (actually or constructively) more than 5% of the total outstanding Public Shares at any time during the applicable period described in (iii).

Distributions

If you are a Non-U.S. Holder who elects to have Public Shares redeemed and the redemption is treated as a distribution for U.S. federal income tax purposes, in general, any distributions AltC makes to you with respect to Public Shares, to the extent paid out of AltC’s current or accumulated earnings and profits (as determined under U.S. federal income tax principles), will constitute a dividend for U.S. federal income tax purposes and, provided such dividends are not effectively connected with your conduct of a trade or business within the United States, AltC would be required to withhold tax from the gross amount of the dividend at a rate of 30%, unless you are eligible for a reduced rate of withholding tax under an applicable income tax treaty and provide proper certification of your eligibility for such reduced rate (on an applicable IRS Form W-8).

Any distribution not constituting a dividend will be treated first as reducing (but not below zero) your adjusted tax basis in your Public Shares and, to the extent such distribution exceeds your adjusted tax basis, as gain realized from the sale or other disposition of the Public Shares, which will be treated as described immediately above.

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The withholding tax does not apply to dividends paid to you if you provide an IRS Form W-8ECI certifying that the dividends are effectively connected with your conduct of a trade or business within the United States. Instead, the effectively connected dividends will be subject to U.S. federal income tax as if you were a U.S. resident. A Non-U.S. Holder that is a corporation that receives effectively connected dividends may also be subject to an additional “branch profits tax” imposed at a rate of 30% (or a lower treaty rate) on the repatriation from the U.S. of its effectively connected earnings and profits for the taxable year, adjusted for certain items.

Each Non-U.S. Holder is urged to consult its tax advisor regarding the U.S. federal income tax considerations to it of a redemption treated as a distribution, including with respect to potentially applicable income tax treaties that may provide for different rules.

FATCA

Sections 1471 to 1474 of the Code (such Sections commonly referred to as the Foreign Account Tax Compliance Act, or “FATCA”) impose a 30% U.S. federal withholding tax on payments of dividends on Public Shares made to (i) a “foreign financial institution,” as defined under such rules, unless such institution enters into an agreement with the Department of Treasury to, among other things, collect and provide to it substantial information regarding such institution’s United States financial account holders, including certain account holders that are non-U.S. entities with United States owners or, in the case of a foreign financial institution in a jurisdiction that has entered into an intergovernmental agreement with the United States, such institution complies with the requirements of such agreement and (ii) a “non-financial foreign entity,” as defined under such rules, unless such entity provides the paying agent with a certification that it does not have any substantial United States owners or a certification identifying the direct and indirect substantial United States owners of the entity, unless in each case, an exemption applies.

Information Reporting and Backup Withholding

Information returns may be filed with the IRS in connection with payments of dividends and the proceeds from a sale or other disposition Public Shares. Non-U.S. Holders may have to comply with certification procedures to establish that such Non-U.S. Holders are not United States persons in order to avoid backup withholding requirements. The certification procedures required to claim a reduced rate of withholding under a treaty will satisfy the certification requirements necessary to avoid the backup withholding as well. Backup withholding is not an additional tax. The amount of any backup withholding from a payment to a Non-U.S. Holder will be allowed as a credit against such Non-U.S. Holder’s U.S. federal income tax liability and may entitle such Non-U.S. Holder to a refund, provided that the required information is timely furnished to the IRS.

State, Local and Non-U.S. Taxes

AltC and the holders of Public Shares may be subject to state, local or non-U.S. taxation in various jurisdictions, including those in which it or they transact business, own property or reside. The state, local or non-U.S. tax treatment of AltC and its stockholders may not conform to the U.S. federal income tax treatment discussed above. Any non-U.S. taxes incurred by AltC would not pass through to stockholders as a credit against their U.S. federal income tax liability. Prospective stockholders should consult their tax advisors regarding the application and effect of state, local and non-U.S. income and other tax laws on a redemption of Public Shares.

As previously noted above, the foregoing discussion of certain material U.S. federal income tax consequences is included for general information purposes only and is not intended to be, and should not be construed as, legal or tax advice to any stockholder. AltC once again urges you to consult with your tax advisor to determine the particular tax consequences to you (including the application and effect of any U.S. federal, state, local or foreign income or other tax laws) of the redemption of Public Shares in connection with the Extension Amendment.

Vote Required for Approval

The approval of the Extension Amendment Proposal requires the affirmative vote of the holders of at least 65% of all the outstanding shares of Common Stock as of the Record Date.

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Recommendation of the Board

THE BOARD UNANIMOUSLY (OF THOSE WHO VOTED) RECOMMENDS THAT
ALTC STOCKHOLDERS VOTE “FOR” THE EXTENSION AMENDMENT PROPOSAL.

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PROPOSAL NO. 2 — THE ADJOURNMENT PROPOSAL

Overview

The Adjournment Proposal, if adopted, will allow the Board to adjourn the Special Meeting to a later date or dates to permit further solicitation of proxies or additional time to effectuate the Extension, if necessary. The Adjournment Proposal will only be presented to AltC’s stockholders in the event there are not sufficient votes at the time of the Special Meeting to approve the Extension Amendment Proposal or if AltC determines that additional time is necessary to effectuate the Extension. In no event will the Board adjourn the Special Meeting beyond October 12, 2023.

Consequences if the Adjournment Proposal is Not Approved

If the Adjournment Proposal is not approved by AltC’s stockholders, the Board may not be able to adjourn the Special Meeting to a later date in the event there are not sufficient votes at the time of the Special Meeting to approve the Extension Amendment Proposal or if AltC determines that additional time is necessary to effectuate the Extension.

Vote Required for Approval

Recommendation of the Board

THE BOARD UNANIMOUSLY (OF THOSE WHO VOTED) RECOMMENDS THAT ALTC
STOCKHOLDERS VOTE “FOR” THE APPROVAL OF THE ADJOURNMENT PROPOSAL.

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BENEFICIAL OWNERSHIP OF SECURITIES

The following table sets forth information regarding the beneficial ownership of our Common Stock as of the Record Date, based on information obtained from the persons named below, with respect to the beneficial ownership of shares of our Common Stock, by:

•

each person known by us to be the beneficial owner of more than 5% of our outstanding shares of Common Stock;

•

each of our named executive officers and directors that beneficially owns shares of our Common Stock; and

•

all our executive officers and directors as a group.

Beneficial ownership is determined according to the rules of the SEC, which generally provide that a person has beneficial ownership of a security if such person possesses sole or shared voting or investment power over that security, including options and warrants that are currently exercisable or exercisable within sixty days.

In the table below, percentage ownership is based on 51,450,000 shares of Class A Common Stock outstanding and 12,500,000 shares of Class B Common Stock outstanding as of the Record Date. On all matters to be voted upon, the holders of the Common Stock vote together as a single class. Shares of Class A Common Stock that may be obtained upon conversion of shares of Class B Common Stock are deemed to be outstanding for the purpose of computing the percentage of beneficial ownership of that person and any group of which that person is a member, but are not deemed outstanding for the purpose of computing the percentage of beneficial ownership for any other person.

Unless otherwise indicated, we believe that all persons named in the table have sole voting and investment power with respect to all shares of Common Stock beneficially owned by them.

Name and Address of Beneficial Owner(1)	Number of Shares Beneficially Owned		Percentage of Outstanding Common Stock
AltC Sponsor LLC(2)(3)		13,950,000		21.8%
Sam Altman(4)		—		—
Michael Klein(2)(3)		13,950,000		21.8%
Jay Taragin(4)		—		—
Frances Frei(4)		—		—
Allison Green(4)		—		—
Peter Lattman(4)		—		—
John L. Thornton(4)		—		—
Empyrean Capital Overseas Master Fund, Ltd(5)		4,847,126		9.4%
Magnetar Financial LLC(6)		3,420,300		6.7%
PEAK6 Capital Management LLC(7)		3,297,000		6.4%
Tiger Global Investments, L.P.(8)		4,000,000		8.0%
Encompass Capital Advisors LLC(9)		2,747,818		5.3%
All directors and officers as a group (7 individuals)(2)(3)(4)		13,950,000		21.8%

(1)

Unless otherwise noted, the business address of each of the following entities or individuals is c/o AltC Acquisition Corp., 640 Fifth Avenue, 12th Floor, New York, NY 10019.

(2)

Interests shown consist of 1,450,000 shares of Class A Common Stock and 12,500,000 shares of Class B Common Stock which are referred to herein as founder shares. Such founder shares will automatically convert into shares of Class A Common Stock at the time of our initial business combination on a one-for-one basis, subject to certain forfeiture provisions as set forth in the Sponsor Agreement.

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(3)

Michael Klein is the controlling stockholder of M. Klein Associates, Inc., which is the managing member of AltC Sponsor LLC. The shares beneficially owned by AltC Sponsor LLC may also be deemed to be beneficially owned by Mr. Klein. This table includes Private Placement Shares purchased by AltC Sponsor LLC.

(4)

Sam Altman, Peter Lattman, Frances Frei and John L. Thornton, all of whom are directors of the Company, and Jay Taragin, the Chief Financial Officer of the Company, each have an economic interest in shares of the Common Stock through his or her direct or indirect ownership of a membership interest or affiliated membership in Sponsor, but do not beneficially own any of our Common Stock. Allison Green, a director of the Company, may be deemed to have an indirect economic interest in the founder shares and Private Placement Shares as a result of Suro Capital Corp. having a membership interest in Sponsor. Ms. Green is the Chief Financial Officer of Suro Capital Corp. The economic interest (or deemed economic interest) of these individuals in the founder shares and Private Placement Shares held by Sponsor is as shown below:

	Founder Shares		Private Placement Shares
Sam Altman		6,035,600		700,100
Allison Green		214,400		24,900
Peter Lattman		128,600		14,900
Fraces Frei		128,600		14,900
John L. Thornton		257,300		29,800
Jay Taragin		5,000		—

(5)

According to the Schedule 13G/A, filed on February 14, 2023, by Empyrean Capital Overseas Master Fund, Ltd., Empyrean Capital Partners, LP and Amos Meron (collectively, the “Empyrean Parties”), the business address of such parties is c/o Empyrean Capital Partners, LP, 10250 Constellation Boulevard, Suite 2950, Los Angeles, CA 90067. The Empyrean Parties hold 4,847,126 shares of Class A Common Stock. Such securities are held through Empyrean Capital Overseas Master Fund, Ltd. (“ECOMF”), a Cayman Islands exempted company, Empyrean Capital Partners, LP (“ECP”), a Delaware limited partnership, which serves as investment manager to ECOMF with respect to the shares of Class A Common Stock directly held by ECOMF; and Mr. Amos Meron, a United States citizen who serves as the managing member of Empyrean Capital, LLC, the general partner of ECP, with respect to the shares of Class A Common Stock directly held by ECOMF.

(6)

According to the Schedule 13G/A, filed on January 27, 2023, by Magnetar Financial LLC (“Magnetar Financial”), a Delaware limited liability company, Magnetar Capital Partners LP (“Magnetar Capital Partners”), a Delaware limited partnership, Supernova Management LLC (“Supernova Management”), a Delaware limited liability company and Mr. David J. Snyderman (“Mr. Snyderman”), a United States citizen who serves as the manager of Supernova Management LLC (collectively, the “Magnetar Parties”), the business address of such parties is 1603 Orrington Avenue, 13th Floor, Evanston, Illinois 60201. The Magnetar Parties hold 3,420,300 shares of Class A Common Stock. The amount consists of (A) 363,055 shares of Class A Common Stock held for the account of Constellation Fund II; (B) 1,151,874 shares of Class A Common Stock held for the account of Constellation Master Fund; (C) 119,800 shares of Class A Common Stock held for the account of Systematic Master Fund; (D) 445,567 shares of Class A Common Stock held for the account of Xing He Master Fund; (E) 204,631 shares of Class A Common Stock held for the account of Purpose Fund; (F) 287,144 shares of Class A Common Stock held for the account of SC Fund; (G) 415,863 shares of Class A Common Stock held for the account of Structured Credit Fund; (H) 359,755 shares of Class A Common Stock held for the account of Lake Credit Fund; and (I) 72,611 shares of Class A Common Stock held for the account of Purpose Fund - T. The shares of Class A Common Stock held by the Magnetar Funds represent approximately 6.65% of the total number of shares of Class A Common Stock outstanding (calculated pursuant to Rule 13d-3(d)(1)(i)) of the outstanding shares of Class A Common Stock). Magnetar Financial serves as the investment adviser to the Magnetar Funds, and as such, Magnetar Financial exercises voting and investment power over the shares of Class A Common Stock held for the Magnetar Funds’ accounts. Magnetar Capital Partners serves as the sole member and parent holding company of Magnetar Financial. Supernova Management is the general partner of Magnetar Capital Partners. The manager of Supernova Management is Mr. Snyderman.

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(7)

According to the Schedule 13G, filed on February 10, 2023, by PEAK6 Capital Management LLC, PEAK6 Group LLC, PEAK6 Investments LLC, PEAK6 LLC, Matthew Hulsizer and Jennifer Just (the “PEAK6 Parties”), the business address of such parties is 141 W. Jackson Blvd, Suite 500, Chicago, IL 60604. The PEAK6 Parties hold 3,297,000 shares of Class A Common Stock.

(8)

According to the Schedule 13G, filed on July 22, 2021, by Tiger Global Investments, L.P., Tiger Global Performance, LLC, Tiger Global Management, LLC, Charles P. Coleman III and Scott Shleifer (the “Tiger Global Parties”), the business address of such parties, with the exception of Tiger Global Investments, L.P., is c/o Tiger Global Management, LLC, 9 West 57th Street, 35th Floor, New York, NY 10019. The business address of Tiger Global Investments, L.P. is c/o Citco Fund Services (Cayman Islands) Limited, P.O. Box 31106, 89 Nexus Way, Camana Bay, Grand Cayman KY1-1205, Cayman Islands. The Tiger Global Parties hold 4,000,000 shares of Class A Common Stock.

(9)

According to the Schedule 13G, filed on September 11, 2023, by Encompass Capital Advisors LLC and Todd J. Kantor (the ‘‘Encompass Parties’’), the business address of such parties is 200 Park Avenue, Suite 1604, New York, NY 10166. The Encompass Parties hold 2,747,818 shares of Class A Common Stock.

FUTURE STOCKHOLDER PROPOSALS

If the Extension Amendment Proposal is approved, we anticipate that we will hold the Business Combination Special Meeting before the Extension Date to consider and vote upon approval of the Business Combination. If the Business Combination is consummated, you will be entitled to attend and participate in the annual meetings of stockholders of the surviving entity following the Business Combination.

HOUSEHOLDING INFORMATION

Unless AltC has received contrary instructions, AltC may send a single copy of this Proxy Statement to any household at which two or more stockholders reside if AltC believes the stockholders are members of the same family. This process, known as “householding,” reduces the volume of duplicate information received at any one household and helps to reduce AltC’s expenses. However, if stockholders prefer to receive multiple sets of AltC’s disclosure documents at the same address this year or in future years, the stockholders should follow the instructions described below. Similarly, if an address is shared with another stockholder and together both of the stockholders would like to receive only a single set of AltC’s disclosure documents, the stockholders should follow these instructions:

•

if the shares are registered in the name of the stockholder, the stockholder should contact AltC at the following address and e-mail address:

AltC Acquisition Corp.
640 Fifth Avenue — 12th Floor
New York, NY 10019
Attention: Jay Taragin, Chief Financial Officer
E-mail: Jay.Taragin@mkleinandcompany.com

•

if a broker, bank or nominee holds the shares, the stockholder should contact the broker, bank or nominee directly.

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WHERE YOU CAN FIND MORE INFORMATION

AltC files reports, proxy statements and other information with the SEC as required by the Exchange Act. You can read AltC’s SEC filings, including this Proxy Statement as well as AltC’s Annual Report on Form 10-K for the year ended December 31, 2022, as amended, over the Internet at the SEC’s website at http://www.sec.gov.

If you would like additional copies of this proxy statement or if you have questions about the Extension or the proposals to be presented at the Special Meeting, you should contact us by telephone or in writing:

AltC Acquisition Corp.
640 Fifth Avenue — 12th Floor
New York, NY 10019
Attention: Jay Taragin, Chief Financial Officer
E-mail: Jay.Taragin@mkleinandcompany.com

You may also obtain these documents by requesting them in writing or by telephone from our proxy solicitor at:

Morrow Sodali LLC
333 Ludlow Street, 5th Floor
South Tower, Stamford CT 06902
Toll-Free (800) 662-5200 or (203) 658-9400
E-mail: ALCC.info@morrowsodali.com

If you are a stockholder of AltC and would like to request documents, please do so by September 28, 2023, to receive them before the Special Meeting. If you request any documents from us, we will mail them to you by first class mail, or another equally prompt means.

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ANNEX A

PROPOSED AMENDMENT
TO THE
AMENDMENT TO THE
AMENDED AND RESTATED
CERTIFICATE OF INCORPORATION
OF
ALTC ACQUISITION CORP.

Pursuant to Section 242 of the
Delaware General Corporation Law

1. The undersigned, being a duly authorized officer of ALTC ACQUISITION CORP. (the “Corporation”), a corporation existing under the laws of the State of Delaware, does hereby certify as follows:

2. The name of the Corporation is AltC Acquisition Corp.

3. The Corporation’s Certificate of Incorporation was filed in the office of the Secretary of State of the State of Delaware on February 1, 2021 and was amended on February 24, 2021. An Amended and Restated Certificate of Incorporation was filed in the office of the Secretary of State of the State of Delaware on July 12, 2021.

4. This Amendment to the Amended and Restated Certificate of Incorporation amends the Amended and Restated Certificate of Incorporation of the Corporation.

5. This Amendment to the Amended and Restated Certificate of Incorporation has been duly adopted in accordance with the provisions of Section 242 of the General Corporation Law of the State of Delaware (the “DGCL”).

6. The text of Section 9.1(b) of Article IX is hereby amended and restated to read in full as follows:

“Immediately after the Offering, a certain amount of the net offering proceeds received by the Corporation in the Offering (including the proceeds of any exercise of the underwriters’ over-allotment option) and certain other amounts specified in the Corporation’s registration statement on Form S-1, as initially filed with the U.S. Securities and Exchange Commission (the “SEC”) on March 15, 2021, as amended (the “Registration Statement”), shall be deposited in a trust account (the “Trust Account”), established for the benefit of the Public Stockholders (as defined below) pursuant to a trust agreement described in the Registration Statement. Except for the amounts withdrawn to fund the Corporation’s working capital requirements, to the extent set forth in the Registration Statement, and/or to pay the Corporation’s taxes (“Permitted Withdrawals”), none of the funds held in the Trust Account (including the interest earned on the funds held in the Trust Account) will be released from the Trust Account until the earliest to occur of (i) the completion of the initial Business Combination, (ii) the redemption of 100% of the Offering Shares (as defined below) if the Corporation is unable to complete its initial Business Combination by July 12, 2024 (or such earlier date as determined by the Board) (the “Completion Window”) or (iii) the redemption of shares in connection with a vote seeking to amend any provisions of this Amended and Restated Certificate as described in Section 9.7. Holders of shares of the Common Stock sold in the Offering (the “Offering Shares”) (whether such Offering Shares were purchased in the Offering or in the secondary market following the Offering and whether or not such holders are affiliates or officers or directors of the Corporation, or affiliates of any of the foregoing) are referred to herein as “Public Stockholders.”

IN WITNESS WHEREOF, I have signed this Amendment to the Amended and Restated Certificate of Incorporation this [•] day of [•], 2023.

ALTC ACQUISITION CORP.

By:

Name: Jay Taragin
Title: Chief Financial Officer

A-1

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FOR AGAINST ABSTAINFOR AGAINST ABSTAINYOUR VOTE IS IMPORTANT. PLEASE VOTE TODAY.Vote by Internet - QUICK EASY IMMEDIATE - 24 Hours a Day, 7 Days a Week or by Mail ALTC ACQUISITION CORP.PLEASE DO NOT RETURN THE PROXY CARD IF YOU ARE VOTING ELECTRONICALLY. Your Internet vote authorizes the named proxies to vote your shares in the same manner as if you marked, signed and returned your proxy card. Votes submitted electronically over the Internet must be received by 11:59 p.m., Eastern Time, on October 4, 2023.INTERNET – www.cstproxyvote.comUse the Internet to vote your proxy. Have your proxy card available when you access the above website. Follow the prompts to vote your shares.Vote at the Meeting –If you plan to attend the virtual online special meeting, you will need your 12 digit control number to vote electronically at the special meeting. To attend: https://www.cstproxy.com/ altcacquisitioncorp/2023MAIL – Mark, sign and date your proxy card and return it in the postage-paid envelope provided. FOLD HERE • DO NOT SEPARATE • INSERT IN ENVELOPE PROVIDEDPROXY CARDPlease markXTHE BOARD OF DIRECTORS RECOMMENDS A VOTE “FOR” PROPOSALS 1 AND 2.your voteslike this 1. Proposal No. 1 — The “Extension Amendment Proposal” — To amend the amended and restated certificate ofincorporation of AltC Acquisition Corp. (“AltC”)(the “Certificate of Incorporation”), in the form set forth in Annex A to the proxy statement to extend the date by which AltC must consummate a merger, capital stock exchange, asset acquisition, stock purchase, reorganization or similar business combination with one or more businesses from October 12, 2023, to July 12, 2024 (or such earlier date as determined by the board of directors of AltC); 2. Proposal No. 2 — The “Adjournment Proposal” — To adjourn the special meeting to a later date or dates, if necessary, to permitfurther solicitation and vote of proxies if, at thetime of the special meeting, there are not sufficient votes to approve the Extension Amendment Proposal or if AltC determines that additional time is necessary to effectuate the Extension. CONTROL NUMBER Signature______________________________ Signature, if held jointly__________________________________ Date_____________, 2023When Shares are held by joint tenants, both should sign. When signing as attorney, executor, administrator, trustee or guardian, please give full title as such. If a corporation, please sign in full corporate name by president or other authorized officer. If a partnership, please sign in partnership name by an authorized person.

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Important Notice Regarding the Availability of Proxy Materials for the Special Meeting of Stockholdersto be held on October 5, 2023This notice of meeting and the accompanying proxy statement are available at https://www.cstproxy.com/altcacquisitioncorp/2023FOLD HERE • DO NOT SEPARATE • INSERT IN ENVELOPE PROVIDEDPROXY CARD FOR SPECIAL MEETING OF STOCKHOLDERS OFALTC ACQUISITION CORP.THIS PROXY IS SOLICITED ON BEHALF OF THE BOARD OF DIRECTORSThe undersigned hereby appoints each of Michael Klein and Jay Taragin (each, a “Proxy”) as proxy, with the power to appoint a substitute to vote the shares that the undersigned is entitled to vote (the “Shares”) at the special meeting of stockholders of AltC Acquisition Corp. to be held on October 5, 2023 at 11 a.m. Eastern Time, virtually via live webcast at https://www.cstproxy.com/altcacquisitioncorp/2023 or at any adjournments and/or postponements thereof. Such Shares shall be voted as indicated with respect to the proposals listed on the reverse side hereof and in the Proxy’s discretion on such other matters as may properly come before the special meeting or any adjournment or postponement thereof.THE SHARES REPRESENTED BY THIS PROXY WHEN PROPERLY EXECUTED WILL BE VOTED IN THE MANNER DIRECTED HEREIN BY THE UNDERSIGNED SHAREHOLDER. IF YOU RETURN A SIGNED AND DATED PROXY CARD BUT NO SPECIFIC DIRECTION IS GIVEN AS TO THE PROPOSALS ON THE REVERSE SIDE, THIS PROXY WILL BE VOTED FOR PROPOSALS 1 AND 2. PLEASE MARK, SIGN, DATE AND RETURN THE PROXY CARD PROMPTLY. (Continued and to be marked, dated and signed on reverse side)