Material Event Form 8 K

Item 8.01.

Other Events.

As previously disclosed, Atlantic Coastal Acquisition Corp. II, a Delaware corporation ("we," "ACAB" the "Company") entered into an agreement (the "Business Combination Agreement") in connection with a proposed business combination (the "Business Combination") with Abpro Corporation, a Delaware Corporation ("Abpro").

As previously disclosed, on October 18, 2024, the Company's Registration Statement on Form S-4(the "Registration Statement") relating to the Business Combination went effective, and the Company filed the proxy statement/prospectus relating to the Business Combination.

On November 8, 2024, the Company filed a Current Report on Form 8-Kand Form 425 (SEC Accession Numbers: 0001193125-24-253658and 0001193125-24-253670,respectively) (collectively, the "First 8-K").Also, on November 8, 2024, the Company filed a Current Report on Form 8-Kand Form 425 (SEC Accession Numbers: 0001193125-24-253672and 0001193125-24-253673,respectively) (collectively, the "Second 8-K",and together with the First 8-K,the "Prior 8-Ks").This Current Report on Form 8-Kcorrects a typographical error in each of the Prior 8-Ksand supersedes each of the Prior 8-Kswith respect to that typographical error.

The reference to "$11.28" in the sentence immediately prior to the heading "Important Information and Where to Find It" in the First 8-Kis replaced with "$11.34", such that the sentence reads as follows:

"As a result of the foregoing, if those holders do not reverse their decision to redeem their shares of Series A common stock will receive a payment of approximately $11.34 per share redeemed."

The reference to "$11.28" in the sentence immediately prior to the heading "Important Information and Where to Find It" in the Second 8-Kis replaced with "$11.34", such that the sentence reads as follows:

"Based upon the current amount in the Trust Account, ACAB estimates that the per share redemption price, assuming estimated withdrawals from the Trust Account to pay franchise and income taxes owed by ACAB, as of November 8, 2024, will be approximately $11.34."

Except as specifically described above, this Current Report on Form 8-Kdoes not amend, modify, or update any disclosures contained in the Prior 8-Ksor the exhibits thereto, including with respect to any events occurring after the furnishing of the Prior 8-Ks.This Current Report on Form 8-Kshould accordingly be read in conjunction with the Prior 8-Ks.

Important Information and Where to Find It

In connection with the Business Combination and the transactions contemplated thereby (the "Proposed Transactions"), ACAB has filed a Registration Statement on Form S-4, asamended, with the Securities and Exchange Commission (the "SEC"), which includes the Proxy Statement distributed to holders of ACAB's common stock in connection with ACAB's solicitation of proxies for the vote by ACAB's stockholders with respect to the Proposed Transactions and other matters as described in the Registration Statement, a prospectus relating to the offer of the securities to be issued to stockholders in connection with the Proposed Transactions. ACAB has mailed a definitive proxy statement/prospectus to its stockholders. Investors and security holders and other interested parties are urged to read the proxy statement/prospectus, any amendments thereto and any other documents filed with the SEC carefully and in their entirety when they become available because they will contain important information about ACAB, Abpro and the Proposed Transactions. When available, investors and security holders may obtain free copies of the definitive proxy statement/prospectus and other documents filed with the SEC by ACAB through the website maintained by the SEC at http://www.sec.gov, or by directing a request to: Atlantic Coastal Acquisition Corp. II, 6 St Johns Lane, Floor 5 New York, NY 10013.

Participants in the Solicitation

ACAB and Abpro and their respective directors and certain of their respective executive officers and other members of management and employees may be considered participants in the solicitation of proxies with respect to the Proposed Transactions. Information about the directors and executive officers of ACAB is set forth in its Annual Report on Form 10-K forthe fiscal year ended December 30, 2023 and the Registration Statement. Additional

information regarding the participants in the proxy solicitation and a description of their direct and indirect interests, by security holdings or otherwise, is included in the Registration Statement and other relevant materials filed, or to be filed, with the SEC regarding the Proposed Transactions. Stockholders, potential investors and other interested persons should read the Registration Statement carefully when it becomes available before making any voting or investment decisions. When available, these documents can be obtained free of charge from the sources indicated above.

No Offer or Solicitation

This Current Report on Form 8-K shallnot constitute an offer to sell or the solicitation of an offer to buy any securities, nor shall there be any sale of securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction. No offering of securities shall be made except by means of a prospectus meeting the requirements of Section 10 of the Securities Act.

Forward-Looking Statements

This Current Report on Form 8-K includescertain statements that are not historical facts but are forward-looking statements for purposes of the safe harbor provisions under the United States Private Securities Litigation Reform Act of 1995. Forward-looking statements generally are accompanied by words such as "believe", "project", "expect", "anticipate", "estimate", "intend", "strategy", "future", "opportunity", "plan", "may", "should", "will", "would", "will be", "will continue", "will likely result" or similar expressions. that predict or indicate future events or trends or that are not statements of historical matters. These forward-looking statements include, but are not limited to, statements regarding estimates and forecasts of revenue and other financial and performance metrics and projections of market opportunity and expectations, ACAB's ability to enter into definitive agreements or consummate a transaction with Abpro; ACAB's ability to obtain the financing necessary consummate the Proposed Transactions; and the expected timing of completion of the Proposed Transactions. These statements are based on various assumptions and on the current expectations of ACAB's and Abpro'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 ACAB and Abpro. These forward looking statements are subject to a number of risks and uncertainties, including general economic, financial, legal, political and business conditions and changes in domestic and foreign markets; the outcome of judicial proceedings to which Abpro is, or may become a party; the inability of the parties to enter into definitive agreements or successfully or timely consummate the Proposed Transactions or to satisfy the other conditions to the closing of the Proposed Transactions, 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; the risk that the approval of the stockholders of ACAB for the Proposed Transactions is not obtained; failure to realize the anticipated benefits of the Proposed Transactions, including as a result of a delay in consummating the Proposed Transaction or difficulty in, or costs associated with, integrating the businesses of ACAB and Abpro; the amount of redemption requests made by ACAB's stockholders; the occurrence of events that may give rise to a right of one or both of ACAB and Abpro to terminate the Business Combination Agreement; risks related to the rollout of Abpro's business and the timing of expected business milestones; the effects of competition on Abpro's future business; and those factors discussed in ACAB's Registration Statement on Form S-1 filedwith the SEC on January 18, 2022, Annual Report on Form 10-K forthe fiscal year ended December 31, 2023, Quarterly Reports on Form 10-Qfor the quarters ended March 31, 2024 and June 30, 2024 and the Registration Statement under the heading "Risk Factors," and other documents of ACAB filed, or to be filed, with the SEC. If the risks materialize or assumptions prove incorrect, actual results could differ materially from the results implied by these forward-looking statements. There may be additional risks that neither ACAB nor Abpro presently know or that ACAB and Abpro 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 ACAB's and Abpro's expectations, plans or forecasts of future events and views as of the date of this Current Report on Form 8-K. ACABand Abpro anticipate that subsequent events and developments will cause their assessments to change. However, while ACAB and Abpro may elect to update these forward-looking statements at some point in the future, ACAB and Abpro specifically disclaim any obligation to do so. These forward-looking statements should not be relied upon as representing ACAB's or Abpro's assessments as of any date subsequent to the date of this Current Report on Form 8-K. Accordingly,undue reliance should not be placed upon the forward-looking statements. Neither ACAB nor Abpro gives any assurance that either ACAB or Abpro, or the combined company, will achieve its objectives.