SC 13G/A 1 p21-0501sc13ga.htm ALTAIR ENGINEERING INC.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G/A

Under the Securities Exchange Act of 1934
(Amendment No. 1)*

Altair Engineering, Inc.
(Name of Issuer)

Class A Common Stock, $0.0001 par value per share
(Title of Class of Securities)

021369103
(CUSIP Number)

December 31, 2020
(Date of Event Which Requires Filing of this Statement)


Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

ý	Rule 13d-1(b)
o	Rule 13d-1(c)
¨	Rule 13d-1(d)

(Page 1 of 7 Pages)

______________________________

*The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

CUSIP No. 021369103

13G/A

Page 2 of 7 Pages

1	NAME OF REPORTING PERSON Matrix Capital Management Company LP
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP		(a) ¨ (b) ¨
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION State of Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH:	5	SOLE VOTING POWER 5,155,025
	6	SHARED VOTING POWER 0
	7	SOLE DISPOSITIVE POWER 5,155,025
	8	SHARED DISPOSITIVE POWER 0
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 5,155,025
10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES			¨
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 11.92%
12	TYPE OF REPORTING PERSON IA, PN

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1	NAME OF REPORTING PERSON David E. Goel
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP		(a) ¨ (b) ¨
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION United States
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH:	5	SOLE VOTING POWER 5,155,025
	6	SHARED VOTING POWER 0
	7	SOLE DISPOSITIVE POWER 5,155,025
	8	SHARED DISPOSITIVE POWER 0
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 5,155,025
10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES			¨
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 11.92%
12	TYPE OF REPORTING PERSON IN

CUSIP No. 021369103

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Item 1(a).	NAME OF ISSUER:

	The name of the issuer is Altair Engineering, Inc., a Delaware corporation (the "Company").

Item 1(b).	ADDRESS OF ISSUER'S PRINCIPAL EXECUTIVE OFFICES:

	The Company's principal executive offices are located at 1820 East Big Beaver Road, Troy, Michigan 48083.

Item 2(a).	NAME OF PERSON FILING:

	This statement is filed by:

	(i)	Matrix Capital Management Company LP (the "Investment Manager"), a Delaware limited partnership, and the investment advisor to Matrix Capital Management Master Fund, LP (the "Matrix Fund"), with respect to the shares of Class A Common Stock (as defined in Item 2(d)) directly held by the Matrix Fund; and

	(ii)	Mr. David E. Goel ("Mr. Goel"), who serves as the Managing General Partner of the Investment Manager, with respect to the shares of Class A Common Stock held by the Matrix Funds.

	The foregoing persons are hereinafter sometimes collectively referred to as the "Reporting Persons."

	The filing of this statement should not be construed as an admission that any of the Reporting Persons is, for the purposes of Section 13 of the Act, the beneficial owner of the shares of Class A Common Stock reported herein.

Item 2(b).	ADDRESS OF PRINCIPAL BUSINESS OFFICE OR, IF NONE, RESIDENCE:

	The address of the business office of each of the Reporting Persons is c/o Matrix Capital Management Company LP, Bay Colony Corporate Center, 1000 Winter Street, Suite 4500, Waltham, MA 02451.

Item 2(c).	CITIZENSHIP:

	The Investment Manager is a Delaware limited partnership. Mr. Goel is a United Stated citizen.

Item 2(d).	TITLE OF CLASS OF SECURITIES:

	Class A Common Stock, par value $0.0001 per share (the "Class A Common Stock").

Item 2(e).	CUSIP NUMBER:

	021369103

CUSIP No. 021369103

13G/A

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Item 3.

IF THIS STATEMENT IS FILED PURSUANT TO RULES 13d-1(b) OR 13d-2(b) OR (c), CHECK WHETHER THE PERSON FILING IS A:

(a)	¨	Broker or dealer registered under Section 15 of the Act (15 U.S.C. 78o);
(b)	¨	Bank as defined in Section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	¨	Insurance company as defined in Section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	¨	Investment company registered under Section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	ý	Investment adviser in accordance with Rule 13d-1(b)(1)(ii)(E);
(f)	¨	Employee benefit plan or endowment fund in accordance with Rule 13d-1(b)(1)(ii)(F);
(g)	ý	Parent holding company or control person in accordance with Rule 13d-1(b)(1)(ii)(G);
(h)	¨	Savings association as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	¨	Church plan that is excluded from the definition of an investment company under Section 3(c)(14) of the Investment Company Act (15 U.S.C. 80a-3);
(j)	¨	Non-U.S. institution in accordance with Rule 13d-1(b)(1)(ii)(J);
(k)	¨	Group, in accordance with Rule 13d-1(b)(1)(ii)(K).

If filing as a non-U.S. institution in accordance with Rule 13d-1(b)(1)(ii)(J), please

specify the type of institution:__________________

Item 4.	OWNERSHIP

	The information required by Items 4(a) – (c) is set forth in Rows (5) – (11) of the cover page for each Reporting Person hereto and is incorporated herein by reference for each such Reporting Person.

	The percentages used herein are calculated based upon 43,242,211 shares of Class A Common Stock outstanding as of October 19, 2020, as reported in the Company's Quarterly Report on Form 10-Q for the quarterly period ended September 30, 2020 filed with the Securities and Exchange Commission on November 5, 2020.

Item 5.	OWNERSHIP OF FIVE PERCENT OR LESS OF A CLASS.

	Not applicable.

Item 6.	OWNERSHIP OF MORE THAN FIVE PERCENT ON BEHALF OF ANOTHER PERSON.

	See Item 2. The Matrix Fund, has the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, more than 5% of the Class A Common Stock.

CUSIP No. 021369103

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Item 7.	IDENTIFICATION AND CLASSIFICATION OF THE SUBSIDIARY WHICH ACQUIRED THE SECURITY BEING REPORTED ON BY THE PARENT HOLDING COMPANY.

	Not applicable.

Item 8.	IDENTIFICATION AND CLASSIFICATION OF MEMBERS OF THE GROUP.

	Not applicable.

Item 9.	NOTICE OF DISSOLUTION OF GROUP.

	Not applicable.

Item 10.

CERTIFICATION.

	Each of the Reporting Persons hereby makes the following certification:

	By signing below each Reporting Person certifies that, to the best of its or his knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect.

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SIGNATURES

After reasonable inquiry and to the best of its or his knowledge and belief, each of the undersigned certifies that the information set forth in this statement is true, complete and correct.

DATE: February 16, 2021

MATRIX CAPITAL MANAGEMENT COMPANY LP


By:	/s/ David E. Goel
Name: David E. Goel
Title: Managing General Partner


/s/ David E. Goel
DAVID E. GOEL