424B3 1 ea0266019-424b3_abpro.htm PROSPECTUS SUPPLEMENT

Filed Pursuant to Rule 424(b)(3)

Registration No. 333-284021

PROSPECTUS SUPPLEMENT NO. 4

(to Prospectus dated May 5, 2025)

ABPRO HOLDINGS, INC.

This prospectus supplement supplements the prospectus dated May 5, 2025 (the “Prospectus”), which forms a part of our registration statement on Form S-1 (No. 333-284021). Capitalized terms used in this prospectus supplement and not otherwise defined herein have the meanings specified in the Prospectus.

This prospectus supplement is being filed to update and supplement the information in the Prospectus with the information contained in our Quarterly Report on Form 10-Q for the fiscal quarter ended September 30, 2025, filed with the Securities and Exchange Commission (the “SEC”) on November 14, 2025 (the “Quarterly Report”). Accordingly, we have attached the Quarterly Report to this prospectus supplement.

Our shares of Common Stock and Public Warrants are currently listed on the Nasdaq Global Market (“Nasdaq”) under the symbols “ABP” and “ABPW,” respectively. On November 14, 2025, the closing price of our Common Stock was $5.49 per share and the closing price of our Public Warrants was $0.02 per Public Warrant.

This prospectus supplement updates and supplements the information in the Prospectus and is not complete without, and may not be delivered or utilized except in combination with, the Prospectus, including any amendments or supplements thereto. This prospectus supplement should be read in conjunction with the Prospectus and if there is any inconsistency between the information in the Prospectus and this prospectus supplement, you should rely on the information in this prospectus supplement.

Investing in our securities involves a high degree of risk. You should review carefully the risks and uncertainties described in the section titled “Risk Factors” beginning on page 7 of the Prospectus, and under similar headings in any amendments or supplements to the Prospectus. Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of the securities to be issued under the Prospectus and this prospectus supplement or determined if the Prospectus and this prospectus supplement is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus supplement is November 17, 2025

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-Q

(MARK ONE)

☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarter ended September 30, 2025

☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from __________ to __________

Commission file number: 001-41224

Abpro Holdings, Inc.

(Exact Name of Registrant as Specified in Its Charter)

Delaware

85-1013956

(State or other jurisdiction of

incorporation or organization)

(I.R.S. Employer

Identification No.)

100 Summit Drive

Burlington, MA 01803

(Address of principal executive offices)

339-227-5961

(Issuer’s telephone number)

(Former name, former address and former fiscal year, if changed since last report)

Securities registered pursuant to Section 12(b) of the Act:

Title of each class	Trading Symbol(s)	Name of each exchange on which registered
Common Stock, par value $0.0001 per share	ABP	The Nasdaq Stock Market LLC
Warrants, each whole warrant exercisable for one share of Common Stock at an exercise price of $114.90	ABPWW	The Nasdaq Stock Market LLC

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ No ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ☒ No ☐

Indicate by check mark whether the registrant is a large, accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company or an emerging growth company. See definitions of “large, accelerated filer”, “accelerated filer”, “smaller reporting company”, and “emerging growth company” in Rule 12b-2 of the Exchange Act.

Large, accelerated filer	☐	Accelerated filer	☐
Non-accelerated filer	☒	Smaller reporting company	☒
		Emerging growth company	☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐ No ☒

As of November 14, 2025, there were 2,716,278 shares of common stock, par value $0.0001 per share, issued and outstanding.

ABPRO HOLDINGS, INC.

FORM 10-Q FOR THE QUARTER ENDED SEPTEMBER 30, 2025

TABLE OF CONTENTS

		Page
Part I. Financial Information		1
Item 1. Financial Statements (Unaudited)		1
Condensed Consolidated Balance Sheets as of September 30, 2025 and December 31, 2024		1
Condensed Consolidated Statements of Operations for the Three and Nine Months Ended September 30, 2025 and 2024		2
Condensed Consolidated Statements of Changes in Stockholders’ Deficit for the Three and Nine Months Ended September 30, 2025 and 2024		3
Condensed Consolidated Statements of Cash Flows for the Nine Months Ended September 30, 2025 and 2024		4
Notes to Unaudited Condensed Consolidated Financial Statements		5
Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations		30
Item 3. Quantitative and Qualitative Disclosures Regarding Market Risk		38
Item 4. Controls and Procedures		38
Part II. Other Information		39
Item 1. Legal Proceedings		39
Item 1A. Risk Factors		39
Item 2. Unregistered Sales of Equity Securities and Use of Proceeds		40
Item 3. Defaults Upon Senior Securities		40
Item 4. Mine Safety Disclosures		40
Item 5. Other Information		40
Item 6. Exhibits		41
Part III. Signatures		42

PART I - FINANCIAL INFORMATION

Item 1. Interim Financial Statements.

ABPRO HOLDINGS, INC.

CONDENSED CONSOLIDATED BALANCE SHEETS

(in thousands except for share and per share data)

	September 30,			December 31,
	2025			2024
	(unaudited)
Assets
Current assets:
Cash	$	328		$	2,850
Accounts receivable		271			271
Prepaid expenses and other current assets		611			358
Forward purchase agreement asset		-			155
Restricted cash		15			142
Total current assets		1,225			3,776

Property and equipment, net		-			37
Right-of-use asset - operating lease		-			418
Security deposits		66			66
Patents, net		169			176
SEPA put rights asset		243			188
Total assets	$	1,703		$	4,661

Liabilities and stockholders’ deficit
Current liabilities:
Accounts payable	$	4,724		$	3,936
Accrued expenses		8,026			7,496
Excise taxes payable		4,401			4,401
Operating lease liability, current		-			456
Income taxes payable		-			366
Notes payable – related parties		147			147
Convertible notes		-			2,725
Embedded derivative liability		-			80
Total current liabilities		17,298			19,607

Commitments and Contingencies (Note 8)

Stockholders' deficit:
Preferred stock, $0.0001 par value, 1,000,000 shares authorized; zero shares issued and outstanding		-			-
Common stock, $0.0001 par value; 110,000,000 shares authorized; 2,672,222 and 1,727,192 shares issued, 2,672,222 and 1,694,414 shares outstanding at September 30, 2025 and December 31, 2024, respectively		-			-
Treasury stock, zero and 32,778 shares at September 30, 2025 and December 31, 2024, respectively, at cost		-			-
Additional paid-in capital		108,487			100,608
Accumulated deficit		(124,631	)		(116,103	)
Total Abpro Holdings, Inc.'s stockholders' deficit		(16,144	)		(15,495	)
Non-controlling interest		549			549
Total stockholders' deficit		(15,595	)		(14,946	)
Total liabilities and stockholders’ deficit	$	1,703		$	4,661

The accompanying notes are an integral part of these unaudited condensed consolidated financial statements.

Reflects a 1-for-30 reverse stock split effective October 31, 2025

ABPRO HOLDINGS, INC.

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS

(in thousands except for share and per share data)

(unaudited)

	For the Three Months Ended September 30,						For the Nine Months Ended September 30,
	2025			2024			2025			2024

Revenue:
Research and development services	$	-		$	183		$	-		$	183

Operating expenses:
Research and development		243			642			881			2,469
General and administrative		1,093			1,472			5,674			4,864
Total operating expenses		1,336			2,114			6,555			7,333

Loss from operations		(1,336	)		(1,931	)		(6,555	)		(7,150	)

Other (expense) income:
Other income		-			-			200			3,556
Change in fair value of forward purchase agreement asset		-			-			(23	)		-
Change in fair value of SEPA put rights asset		230			-			55			-
Change in fair value of embedded derivative liability		(150	)		-			(773	)		-
Loss on settlement of convertible notes		(214	)		-			(358	)		-
Interest income		6			2			30			3
Interest expense		(193	)		(164	)		(1,104	)		(306	)
Total other (expense) income, net		(321	)		(162	)		(1,973	)		3,253

Net loss	$	(1,657	)	$	(2,093	)	$	(8,528	)	$	(3,897	)

Net loss per share, basic and diluted	$	(0.63	)	$	(3.27	)	$	(4.12	)	$	(6.09	)

Weighted averages shares outstanding
Weighted average shares outstanding - basic and diluted		2,613,889			640,606			2,069,965			639,996

The accompanying notes are an integral part of these unaudited condensed consolidated financial statements.

Reflects a 1-for-30 reverse stock split effective October 31, 2025

ABPRO HOLDINGS, INC.

CONDENSED CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS’ DEFICIT

(in thousands except share and per share data)

(unaudited)

	Series A Redeemable,				Series B				Series C				Series D				Series E				Series F				Total Convertible																	Total
	Convertible Preferred Stock				Convertible Preferred Stock				Convertible Preferred Stock				Convertible Preferred Stock				Convertible Preferred Stock				Convertible Preferred Stock				Preferred Stock		Common Stock					Treasury Stock					Additional Paid-In		Accumulated			Abpro’s Stockholders’			Non-controlling		Total Stockholders’
	Shares		Amount		Shares		Amount		Shares		Amount		Shares		Amount		Shares		Amount		Shares		Amount		Amount		Shares			Amount		Shares			Amount		Capital		Deficit			Deficit			Interest		Deficit
Balances, as of December 31, 2024		-	$	-		-	$	-		-	$	-		-	$	-		-	$	-		-	$	-	$	-		1,727,192		$	-		(32,778	)	$	-	$	100,608	$	(116,103	)	$	(15,495	)	$	549	$	(14,946	)

Common stock issued for services		-		-		-		-		-		-		-		-		-		-		-		-		-		5,000			-		-			-		-		-			-			-		-

Warrants issued to related party lender		-		-		-		-		-		-		-		-		-		-		-		-		-		-			-		-			-		714		-			714			-		714

Share-based compensation		-		-		-		-		-		-		-		-		-		-		-		-		-		-			-		-			-		308		-			308			-		308

Net loss		-		-		-		-		-		-		-		-		-		-		-		-		-		-			-		-			-		-		(3,887	)		(3,887	)		-		(3,887	)

Balances, as of March 31, 2025		-		-		-		-		-		-		-		-		-		-		-		-		-		1,732,192			-		(32,778	)		-		101,630		(119,990	)		(18,360	)		549		(17,811	)

Share-based compensation		-		-		-		-		-		-		-		-		-		-		-		-		-		-			-		-			-		154		-			154			-		154

Common stock issued upon conversion of convertible notes		-		-		-		-		-		-		-		-		-		-		-		-		-		513,981			-		-			-		3,694		-			3,694			-		3,694

Net loss		-		-		-		-		-		-		-		-		-		-		-		-		-		-			-		-			-		-		(2,984	)		(2,984	)		-		(2,984	)

Balances, as of June 30, 2025		-		-		-		-		-		-		-		-		-		-		-		-		-		2,246,173			-		(32,778	)		-		105,478		(122,974	)		(17,496	)		549		(16,947	)

Share-based compensation		-		-		-		-		-		-		-		-		-		-		-		-		-		-			-		-			-		78		-			78			-		78

Common stock issued upon conversion of convertible notes		-		-		-		-		-		-		-		-		-		-		-		-		-		367,491			-		-			-		2,243		-			2,243			-		2,243

Issuance of Advance Shares, net of issuance costs		-		-		-		-		-		-		-		-		-		-		-		-		-		91,336			-		-			-		688		-			688			-		688

Cancellation of Treasury Stock		-		-		-		-		-		-		-		-		-		-		-		-		-		(32,778	)		-		32,778			-		-		-			-			-		-

Net loss		-		-		-		-		-		-		-		-		-		-		-		-		-		-			-		-			-		-		(1,657	)		(1,657	)		-		(1,657	)

Balances, as of September 30, 2025		-	$	-		-	$	-		-	$	-		-	$	-		-	$	-		-	$	-	$	-		2,672,222		$	-		-		$	-	$	108,487	$	(124,631	)	$	(16,144	)	$	549	$	(15,595	)

	Series A Redeemable,				Series B				Series C				Series D				Series E				Series F				Total Convertible																	Total
	Convertible Preferred Stock				Convertible Preferred Stock				Convertible Preferred Stock				Convertible Preferred Stock				Convertible Preferred Stock				Convertible Preferred Stock				Preferred Stock		Common Stock				Treasury Stock						Additional Paid-In		Accumulated			Abpro’s Stockholders’			Non-controlling		Total Stockholders’
	Shares		Amount		Shares		Amount		Shares		Amount		Shares		Amount		Shares		Amount		Shares		Amount		Amount		Shares		Amount		Shares			Amount			Capital		Deficit			Deficit			Interest		Deficit
Balances, as of December 31, 2023		3,938,098	$	1,795		1,281,402	$	1,401		4,101,409	$	14,949		2,679,397	$	17,622		6,756,246	$	29,841		1,136,049	$	9,991	$	75,599		646,044	$	-		(7,006	)	$	(33	)	$	19,920	$	(108,871	)	$	(88,984	)	$	549	$	(88,435	)

Vesting of restricted stock units		-		-		-		-		-		-		-		-		-		-		-		-		-		639		-		-			-			-		-			-			-		-

Share-based compensation		-		-		-		-		-		-		-		-		-		-		-		-		-		-		-		-			-			563		-			563			-		563

Net income		-		-		-		-		-		-		-		-		-		-		-		-		-		-		-		-			-			-		636			636			-		636

Balances, as of March 31, 2024		3,938,098		1,795		1,281,402		1,401		4,101,409		14,949		2,679,397		17,622		6,756,246		29,841		1,136,049		9,991		75,599		646,683		-		(7,006	)		(33	)		20,483		(108,235	)		(87,785	)		549		(87,236	)

Vesting of restricted stock units		-		-		-		-		-		-		-		-		-		-		-		-		-		639		-		-			-			-		-			-			-		-

Share-based compensation		-		-		-		-		-		-		-		-		-		-		-		-		-		-		-		-			-			553		-			553			-		553

Net loss		-		-		-		-		-		-		-		-		-		-		-		-		-		-		-		-			-			-		(2,440	)		(2,440	)		-		(2,440	)

Balances, as of June 30, 2024		3,938,098		1,795		1,281,402		1,401		4,101,409		14,949		2,679,397		17,622		6,756,246		29,841		1,136,049		9,991		75,599		647,322		-		(7,006	)		(33	)		21,036		(110,675	)		(89,672	)		549		(89,123	)

Vesting of restricted stock units		-		-		-		-		-		-		-		-		-		-		-		-		-		554		-		-			-			-		-			-			-		-

Share-based compensation		-		-		-		-		-		-		-		-		-		-		-		-		-		-		-		-			-			415		-			415			-		415

Net loss		-		-		-		-		-		-		-		-		-		-		-		-		-		-		-		-			-			-		(2,093	)		(2,093	)		-		(2,093	)

Balances, as of September 30, 2024		3,938,098	$	1,795		1,281,402	$	1,401		4,101,409	$	14,949		2,679,397	$	17,622		6,756,246	$	29,841		1,136,049	$	9,991	$	75,599		647,876	$	-		(7,006	)	$	(33	)	$	21,451	$	(112,768	)	$	(91,350	)	$	549	$	(90,801	)

The accompanying notes are an integral part of these unaudited condensed consolidated financial statements.

Reflects a 1-for-30 reverse stock split effective October 31, 2025

ABPRO HOLDINGS, INC.

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS

(in thousands except share and per share data)

(unaudited)

	For the Nine Months Ended September 30,
	2025			2024
Cash Flows from Operating Activities:
Net loss	$	(8,528	)	$	(3,897	)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense		18			67
Share-based compensation		1,158			1,531
Amortization of operating lease right-of-use assets		418			408
Non-cash interest expense		854			53
Loss on settlement of convertible notes		358			-
Other income (see Note 2)		(200	)		(3,556	)
Amortization of debt discount		160			-
Change in fair value of forward purchase agreement asset		23			-
Change in fair value of SEPA put rights asset		(55	)		-
Change in fair value of embedded derivative liability		773			-
Changes in operating assets and liabilities:
Accounts receivable		-			(183	)
Prepaid expenses and other current assets		(257	)		(93	)
Accounts payable		787			325
Accrued expenses		(73	)		551
Income taxes payable		(366	)		-
Operating lease liability		(456	)		(421	)
Net cash used in operating activities

SEC Form 424B3 filed by Abpro Holdings Inc