ACABU Atlantic Coastal Acquisition Corporation II

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

(Amendment No. )

Filed by the Registrant  ☒

Filed by a Party other than the Registrant  ☐

Check the appropriate box:

Atlantic Coastal Acquisition Corp. II

(Name of Registrant as Specified In Its Charter)

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

Payment of Filing Fee (Check the appropriate box):

ATLANTIC COASTAL ACQUISITION CORP. II

6 St Johns Lane, Floor 5

New York, NY 10013

NOTICE OF SPECIAL MEETING OF STOCKHOLDERS

To Be Held December 15, 2023

TO THE STOCKHOLDERS OF ATLANTIC COASTAL ACQUISITION CORP. II:

You are cordially invited to attend the special meeting, which we refer to as the “Special Meeting,” of stockholders of Atlantic Coastal Acquisition Corp. II, which we refer to as “we,” “us,” “our,” “ACAB” or the “Company,” to be held at 3:00 p.m. Eastern Time on December 15, 2023.

The Special Meeting will be a completely virtual meeting of stockholders, which will be conducted via live webcast. You will be able to attend, vote and submit your questions during the Special Meeting by visiting https://www.cstproxy.com/atlanticcoastalacquisitionii/sm2023. 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. We are pleased to utilize the virtual stockholder meeting technology to provide ready access and cost savings for our stockholders and the Company. The virtual meeting format allows attendance from any location in the world.

Even if you are planning on attending the Special Meeting online, please promptly submit your proxy vote by telephone, or, if you received a printed form of proxy in the mail, by completing, dating, signing and returning the enclosed proxy, so your shares will be represented at the Special Meeting.

Instructions on voting your shares are on the proxy materials you received for the Special Meeting. Even if you plan to attend the Special Meeting online, it is strongly recommended you complete and return your proxy card before the Special Meeting date, to ensure that your shares will be represented at the Special Meeting if you are unable to attend.

The accompanying proxy statement, which we refer to as the “Proxy Statement,” is dated December 1, 2023, and is first being mailed to stockholders of the Company on or about December 7, 2023. The sole purpose of the Special Meeting is to consider and vote upon the following proposals:

Each of the Charter Amendment Proposal and the Adjournment Proposal is more fully described in the accompanying Proxy Statement.

If the Charter Amendment Proposal is approved and the Charter Amendment becomes effective, the Sponsor will deposit the lesser of (a) $30,000 or (b) $0.045 for each public share that is not redeemed in connection with the Special Meeting. In the event that ACAB has not consummated a business combination by the Extended Date, without approval of the holders of ACAB’s public shares (as defined below), ACAB may, by resolution of the Board, if requested by the Sponsor, and upon five days’ advance notice prior to the applicable Termination Date, extend the Termination Date up to six times, each by one additional month (for a total of up to nine additional months to complete a business combination), provided that the Sponsor (or one or more of its affiliates, members or third-party designees) (the “Payor”) will deposit into the Trust Account: for each such monthly extension, the lesser of (a) $10,000 or (b) $0.015 for each public share that is not redeemed in connection with the Special Meeting for an aggregate deposit of up to the lesser of (x) $60,000 or (y) $0.09 for each public share that is not redeemed in connection with the Special Meeting (if all six additional monthly extensions are exercised).

The purpose of the Charter Amendment Proposal and, if necessary, the Adjournment Proposal, is to allow us additional time to complete a business combination. We entered into a term sheet with Abpro Corporation (“Abpro”), a biotechnology company, on September 18, 2023, which sets forth the terms and conditions of a potential business combination with Abpro. As of the date of this proxy statement, we are actively negotiating a definitive agreement with Abpro. The term sheet provides for an exclusivity period currently expected to expire sixty days from September 18, 2023. There is no fee or penalty for either party in the event the term sheet is terminated or the contemplated business combination is not consummated. While we are using our best efforts to complete a business combination as soon as practicable, our Board believes that there will not be sufficient time before the Original Termination Date to complete an initial business combination with Abpro or any other party. Accordingly, the Board believes that in order to be able to consummate a business combination, we will need to obtain an Extension. Without an Extension, the Board believes that there is significant risk that we might not, despite our best efforts, be able to complete a business combination on or before the Original Termination Date. If that were to occur, we would be precluded from completing a business combination and would be forced to liquidate even if our stockholders are otherwise in favor of consummating a business combination.

Therefore, the Board has determined that it is in the best interests of our stockholders to extend the date by which the Company has to consummate a business combination to the Extended Date (or Additional Charter Extension Date, if applicable) in order that our stockholders have the opportunity to participate in our future investment.

In the event that we enter into a definitive agreement for an initial business combination prior to the Special Meeting, we will issue a press release and file a Current Report on Form 8-K with the U.S. Securities and Exchange Commission (the “SEC”) announcing the proposed business combination. If the Extension to the Extended Date is approved and implemented, we intend to complete a business combination as soon as possible and in any event on or before the applicable Termination Date.

In connection with the Charter Amendment Proposal, public stockholders may elect to redeem their public shares for a per-share price, payable in cash, equal to the aggregate amount then on deposit in the trust account (the “Trust Account”), including interest (which interest shall be net of taxes payable), divided by the number of then outstanding shares of Series A common stock issued in our IPO, which shares we refer to as the “public shares,” and which election we refer to as the “Election,” regardless of whether such public stockholders vote on the Charter Amendment Proposal. Any redemptions by the Company as a result of an Election shall be conditioned on the approval of the Charter Amendment Proposal by the requisite vote of shareholders.

If the Charter 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 a business combination is submitted to the stockholders, subject to any limitations set forth in our charter as amended by the Charter Amendment. In addition, if the Charter Amendment Proposal is approved, public stockholders who do not make the Election would be entitled to have their public shares redeemed for cash if the Company has not completed a business combination by the Extended Date (or Additional Charter Extension Date, if applicable). Even if the Charter Amendment is approved, we can provide no assurances that a business combination will be consummated prior to the Extended Date (or Additional Charter Extension Date, if applicable). Furthermore, the Board, in its discretion, may nevertheless decide to liquidate the Company even prior to the applicable Termination Date if it is in the best interest of our stockholders.

To exercise your redemption rights, you must demand that the Company redeem your public shares for a pro rata portion of the funds held in the Trust Account, and tender your shares to the Company’s transfer agent at least two business days prior to the Special Meeting (or December 13, 2023). 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 you hold your shares in street name, you will need to instruct your bank, broker or other nominee to withdraw the shares from your account in order to exercise your redemption rights. The redemption rights include the requirement that a stockholder must identify itself in writing as a beneficial holder and provide its legal name, phone number, and address in order to validly redeem its public shares.

With respect to the regulation of special purpose acquisition companies (“SPACs”) like ACAB, on March 30, 2022, the SEC issued proposed rules relating to, among other items, the extent to which SPACs could become subject to regulation under the Investment Company Act of 1940, as amended. The proposal is consistent with less formal positions recently taken by the staff of the SEC. To mitigate the risk of us being deemed to have been operating as an unregistered investment company (including under the subjective test of Section 3(a)(1)(A) of the Investment Company Act), on or prior to the 24-month anniversary of the effective date of our registration statement relating to our initial public offering, we will instruct the Trustee with respect to the Trust Account, to liquidate the U.S. government securities or money market funds held in the Trust Account and thereafter to hold all funds in the Trust Account in cash (which may include demand deposit accounts) until the earlier of the consummation of our business combination or liquidation. Currently, all funds in the Trust Account are held in U.S. government securities or money market funds. The longer the funds in the Trust Account are held in such U.S. government securities or money market funds, the greater the risk that the Company will be deemed to be an unregistered investment company under the Investment Company Act.

Based upon the current amount in the Trust Account, the Company anticipates that the per-share price at which public shares will be redeemed from cash held in the Trust Account will be approximately $10.68 at the time of the Special Meeting. The closing price of the Company’s Series A common stock on November 30, 2023 was $10.60. The Company cannot assure stockholders that they will be able to sell their shares of the Company’s Series A common stock 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.

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. The Adjournment Proposal will only be presented to our stockholders in the event that there are insufficient votes for, or otherwise in connection with, the approval of the Charter Amendment Proposal.

If the Charter Amendment Proposal is not approved, we will not redeem any shares in respect of which public stockholders have made an Election, and will, as promptly as reasonably practicable, and in any event within 5 business days, return any shares tendered to the Company’s transfer agent prior to the Special Meeting. Further, if the Charter Amendment is not approved and we do not consummate a business combination by December 19, 2023, in accordance with our charter, we 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, redeem 100% of the public shares, at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account, including interest earned and not previously released to the Company to pay its taxes, if any (less taxes payable and up to $100,000 of such net interest to pay dissolution expenses), divided by the number of then issued and outstanding public shares, which redemption will completely extinguish the rights of the Public Stockholders (as defined in the charter) as 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 Company’s remaining stockholders and the Company’s board of directors, dissolve and liquidate, subject (in the case of (ii) and (iii) above) to the Company’s obligations under the Delaware General Corporation Law, which we refer to as the “DGCL,” to provide for claims of creditors and other requirements of applicable law. There will be no distribution from the Trust Account with respect to our warrants, which will expire worthless in the event of our winding up.

Our Sponsor owns 7,200,000 Founder Shares (as defined below), which amount includes 825,225 Founder Shares which may be subject to transfer upon the consummation of a business combination pursuant to the terms of non-redemption agreements by and between the Sponsor and several unaffiliated third parties (as detailed in the Company’s Form 8-K filed on April 18, 2023), and 13,850,000 private placement warrants, which we refer to as the “Private Placement Warrants,” that were purchased by the Sponsor in a private placement which occurred simultaneously with the completion of the IPO. In addition, each of our independent directors and an advisor to us owns 50,000 Founder Shares. As used herein, “Founder Shares” refers to all issued and outstanding shares of our Series B common stock and any shares of our Series B common stock that were subsequently converted into shares of Series A common stock (such converted shares not having redemption rights nor being publicly tradable nor having voting rights with respect to the matters herein). In the event of a liquidation, our Sponsor, officers and directors will not receive any monies held in the Trust Account as a result of their ownership of the Founder Shares, the Private Placement Warrants or any Series A common stock issued in connection with the conversion of the Founder Shares.

Subject to the foregoing, the affirmative vote of at least 65% of the Company’s outstanding shares of common stock entitled to vote will be required to approve the Charter Amendment Proposal. Stockholder approval of the Charter Amendment is required for the implementation of our Board’s plan to extend the date by which we must consummate our initial business combination. Notwithstanding stockholder approval of the Charter Amendment Proposal, our Board will retain the right to abandon and not implement the Charter Amendment at any time without any further action by our stockholders.

Approval of the Adjournment Proposal requires the affirmative vote of the majority of the votes cast by stockholders represented in person or by proxy at the Special Meeting.

Our Board has fixed the close of business on November 8, 2023 as the date for determining the Company stockholders entitled to receive notice of and vote at the Special Meeting and any adjournment thereof. Only certain holders of record of the Company’s common stock on that date are entitled to have their votes counted at the Special Meeting or any adjournment thereof.

We reserve the right at any time to cancel the Special Meeting and not to submit to our stockholders the Charter Amendment Proposal and implement the Charter Amendment. In the event the Special Meeting is cancelled, we may dissolve and liquidate in accordance with the charter.

You are not being asked to vote on a business combination at this time. If the Charter Amendment is implemented and you do not elect to redeem your public shares, provided that you are a stockholder on the record date for a meeting to consider a business combination, you will retain the right to vote on a

business combination when it is submitted to stockholders and the right to redeem your public shares for cash in the event a business combination is approved and completed or we have not consummated a business combination by the Extended Date (or Additional Charter Extension Date, if applicable).

After careful consideration of all relevant factors, the Board has determined that the Charter Amendment Proposal and, if presented, the Adjournment Proposal are advisable and recommends that you vote or give instruction to vote “FOR” such proposals.

Under Delaware law and the Company’s bylaws, no other business may be transacted at the Special Meeting.

Enclosed is the Proxy Statement containing detailed information concerning the Charter Amendment Proposal, the Adjournment Proposal and the Special Meeting. Whether or not you plan to attend the Special Meeting, we urge you to read this material carefully and vote your shares.

Your vote is important. If you are a stockholder of record, please sign, date and return your proxy card as soon as possible to make sure that your shares are represented at the Special Meeting. If you are a stockholder of record, you may also cast your vote online at the Special Meeting. If your shares are held in an account at a brokerage firm or bank, you must instruct your broker or bank how to vote your shares, or you may cast your vote online at the Special Meeting by obtaining a proxy from your brokerage firm or bank. Your failure to vote or instruct your broker or bank how to vote will have the same effect as voting “AGAINST” the Charter Amendment Proposal, and an abstention will have the same effect as voting “AGAINST” the Charter Amendment Proposal.

Important Notice Regarding the Availability of Proxy Materials for the Special Meeting of Stockholders to be held on December 15, 2023: This notice of meeting and the accompanying Proxy Statement are available at https://www.cstproxy.com/atlanticcoastalacquisitionii/sm2023.

ATLANTIC COASTAL ACQUISITION CORP. II

6 St Johns Lane, Floor 5

New York, NY 10013

NOTICE OF SPECIAL MEETING OF STOCKHOLDERS

TO BE HELD December 15, 2023

PROXY STATEMENT

The special meeting, which we refer to as the “Special Meeting,” of stockholders of Atlantic Coastal Acquisition Corp. II, which we refer to as “we,” “us,” “our,” “ACAB” or the “Company,” to be held at 3:00 p.m. Eastern Time on December 15, 2023, as a virtual meeting. You will be able to attend, vote your shares, and submit questions during the Special Meeting via a live webcast available at https://www.cstproxy.com/atlanticcoastalacquisitionii/sm2023. 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. The Special Meeting will be held for the sole purpose of considering and voting upon the following proposals:

If the Charter Amendment Proposal is approved and the Charter Amendment becomes effective, the Sponsor will deposit the lesser of (a) $30,000 or (b) $0.045 for each public share that is not redeemed in connection with the Special Meeting. In the event that ACAB has not consummated a business combination by the Extended Date, without approval of the holders of ACAB’s public shares (as defined below), ACAB may, by resolution of the Board, if requested by the Sponsor, and upon five days’ advance notice prior to the applicable Termination Date, extend the Termination Date up to six times, each by one additional month (for a total of up to nine additional months to complete a business combination), provided that the Sponsor (or one or more of its affiliates, members or third-party designees) (the “Payor”) will deposit into the Trust Account: for each such monthly extension, the lesser of (a) $10,000 or (b) $0.015 for each public share that is not redeemed in

connection with the Special Meeting for an aggregate deposit of up to the lesser of (x) $60,000 or (y) $0.09 for

each public share that is not redeemed in connection with the Special Meeting (if all six additional monthly extensions are exercised).

The purpose of the Charter Amendment Proposal and, if necessary, the Adjournment Proposal, is to allow us additional time to complete a business combination. We entered into a term sheet with Abpro Corporation (“Abpro”), a biotechnology company, on September 18, 2023, which sets forth the terms and conditions of a potential business combination with Abpro. As of the date of this proxy statement, we are actively negotiating a definitive agreement with Abpro. The term sheet provides for an exclusivity period currently expected to expire sixty days from September 18, 2023. There is no fee or penalty for either party in the event the term sheet is terminated or the contemplated business combination is not consummated. While we are using our best efforts to complete a business combination as soon as practicable, our board of directors believes that there will not be sufficient time before the Original Termination Date to complete an initial business combination with Abpro or any other party. Accordingly, the Board believes that in order to be able to consummate a business combination, we will need to obtain an Extension. Without an Extension, the Board believes that there is significant risk that we might not, despite our best efforts, be able to complete a business combination on or before the Original Termination Date. If that were to occur, we would be precluded from completing a business combination and would be forced to liquidate even if our stockholders are otherwise in favor of consummating a business combination.

In the event that we enter into a definitive agreement for an initial business combination prior to the Special Meeting, we will issue a press release and file a Current Report on Form 8-K with the U.S. Securities and Exchange Commission (the “SEC”) announcing the proposed business combination. If the Extension to the Extended Date is approved and implemented, we intend to complete a business combination as soon as possible and in any event on or before the applicable Termination Date.

The Charter Amendment Proposal is required for the implementation of the plan of the Board, to extend the date by which the Company has to complete our business combination. The purpose of the Charter Amendment is to allow the Company more time to complete a business combination. In addition, we will not proceed with the Extension to the Extended Date and any redemptions in connection therewith if the number of redemptions or repurchases of our shares of Series A common stock issued in our IPO, which shares we refer to as the “public shares,” causes us to have less than $5,000,001 of net tangible assets following approval of the Charter Amendment Proposal.

In connection with the Charter Amendment Proposal, public stockholders may elect to redeem their public shares for a per-share price, payable in cash, equal to the aggregate amount then on deposit in the trust account (the “Trust Account”), including interest (which interest shall be net of taxes payable), divided by the number of then outstanding shares of Series A common stock issued in our IPO, which shares we refer to as the “public shares,” and which election we refer to as the “Election,” regardless of whether such public stockholders vote on the Charter Amendment Proposal. We cannot predict the amount that will remain in the Trust Account if the Charter Amendment Proposal is approved and the amount remaining in the Trust Account may be only a small fraction of the approximately $36.7 million that was in the Trust Account as of November 8, 2023, the record date. Any redemptions by the Company as a result of an Election shall be conditioned on the approval of the Charter Amendment Proposal by the requisite vote of shareholders.

If the Charter 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 a business combination is submitted to the stockholders, subject to any limitations set forth in our charter as amended by the Charter Amendment. In addition, if the Charter Amendment Proposal is approved, public stockholders who do not make the Election would be entitled to have their public shares redeemed for cash if the Company has not completed a business combination by the Extended Date (or Additional Charter Extension Date, if applicable). Even if the Charter Amendment is approved, we can provide no assurances that a business combination will be consummated prior to the Extended Date (or Additional Charter Extension Date, if applicable). Furthermore, the Board, in its discretion, may nevertheless decide to liquidate the Company even prior to the applicable Termination Date if it is in the best interest of our stockholders.

The Sponsor owns 7,200,000 Founder Shares (as defined below), which amount includes 825,225 Founder Shares which may be subject to transfer upon the consummation of a business combination pursuant to the terms of non-redemption agreements by and between the Sponsor and several unaffiliated third parties (as detailed in the Company’s Form 8-K filed on April 18, 2023), and 13,850,000 private placement warrants, which we refer to as the “Private Placement Warrants,” that were purchased by the Sponsor in a private placement which occurred simultaneously with the completion of the IPO. In addition, each of our independent directors and an advisor to us owns 50,000 Founder Shares. As used herein, “Founder Shares” refers to all issued and outstanding shares of our Series B common stock and any shares of our Series B common stock that were subsequently converted into shares of Series A common stock (such converted shares not having redemption rights nor being publicly tradable nor having voting rights with respect to the matters herein). In the event of a liquidation, our Sponsor, officers and directors will not receive any monies held in the Trust Account as a result of their ownership of the Founder Shares, the Private Placement Warrants or any Series A common stock issued in connection with the conversion of the Founder Shares.

To exercise your redemption rights, you must demand that the Company redeem your public shares for a pro rata portion of the funds held in the Trust Account, and tender your shares to the Company’s transfer agent at least two business days prior to the Special Meeting (or December 13, 2023). 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 you hold your shares in street name, you will need to instruct your bank, broker or other nominee to withdraw the shares from your account in order to exercise your redemption rights. The redemption rights include the requirement that a stockholder must identify itself in writing as a beneficial holder and provide its legal name, phone number, and address in order to validly redeem its public shares.

Based upon the current amount in the Trust Account, the Company anticipates that the per-share price at which public shares will be redeemed from cash held in the Trust Account will be approximately $10.68 at the time of the Special Meeting. The closing price of the Company’s Series A common stock on November 30, 2023, the most recent practicable date prior to the date of this proxy statement was $10.60. The Company cannot assure stockholders that they will be able to sell their shares of the Company’s Series A common stock 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.

Approval of the Charter Amendment Proposal is a condition to the implementation of the Extension to the Extended Date and the consummation of redemptions in connection therewith. In addition, we will not proceed with the Extension to the Extended Date if the number of redemptions or repurchases of our shares of Series A common stock issued in our IPO, which shares we refer to as the “public shares,” causes us to have less than $5,000,001 of net tangible assets following approval of the Charter Amendment Proposal.

If the Charter Amendment Proposal is not approved, we will not redeem any shares in respect of which public stockholders have made an Election, and will, as promptly as reasonably practicable, and in any event within 5 business days, return any shares tendered to the Company’s transfer agent prior to the Special Meeting. Further, if the Charter Amendment is not approved and we do not consummate a business combination by December 19, 2023, in accordance with our charter, we 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, redeem 100% of the public shares, at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account, including interest earned and not previously released to the Company to pay its taxes, if any (less taxes payable and up to $100,000 of such net interest to pay dissolution expenses), divided by the number of then issued and outstanding public shares, which redemption will completely extinguish the rights of the Public Stockholders (as defined in the charter) as 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 Company’s remaining stockholders and the Company’s board of directors, dissolve and liquidate, subject (in the case of (ii) and (iii) above) to the Company’s obligations under the Delaware General Corporation Law, which we refer to as the “DGCL,” to provide for claims of creditors and other requirements of applicable law.

There will be no distribution from the Trust Account with respect to our warrants, which will expire worthless in the event of our winding up. In the event of a liquidation, our Sponsor will not receive any monies held in the Trust Account as a result of its ownership of 7,200,000 Founder Shares and 13,850,000 private placement warrants, which we refer to as the “Private Placement Warrants,” that were purchased by the Sponsor in a private placement which occurred simultaneously with the completion of the IPO. In addition, each of our independent directors and an advisor to us owns 50,000 Founder Shares.

We reserve the right at any time to cancel the Special Meeting and not to submit to our stockholders the Charter Amendment Proposal and implement the Charter Amendment. In the event the Special Meeting is cancelled, we may dissolve and liquidate in accordance with the charter.

Our Sponsor has agreed that it will be liable to us if and to the extent any claims by a third party (other than our independent registered public accounting firm) for services rendered or products sold to us, or a prospective target business with which we have discussed entering into a transaction agreement, reduce the amount of funds in the Trust Account to below (1) $10.20 per public share or (2) such lesser amount per public share held in the Trust Account as of the date of the liquidation of the Trust Account due to reductions in the value of the trust assets, in each case net of the interest which may be withdrawn to pay our franchise and income taxes (less up to $100,000 of interest to pay dissolution expenses), except as to any claims by a third party who executed a waiver of any and all rights to seek access to the Trust Account and except as to any claims under our indemnity of the underwriters of our initial public offering against certain liabilities, including liabilities under the Securities Act. Moreover, in the event that an executed waiver is deemed to be unenforceable against a third party, our Sponsor will not be responsible to the extent of any liability for such third-party claims. We have not independently verified whether our Sponsor has sufficient funds to satisfy its indemnity obligations and believe that our Sponsor’s only assets are securities of our company and, therefore, our Sponsor may not be able to satisfy those obligations. We have not asked our Sponsor to reserve for such obligations. As a result, if any such claims were successfully made against the Trust Account, the funds available for our initial business combination and redemptions could be reduced to less than $10.20 per public share. In such event, we may not be able to complete our initial business combination, and you would receive such lesser amount per share in connection with any redemption of your public shares. None of our officers or directors will indemnify us for claims by third parties including, without limitation, claims by vendors and prospective target businesses. Based upon the current amount in the Trust Account, we anticipate that the per-share price at which public shares will be redeemed from cash held in the Trust Account will be approximately $10.68. Nevertheless, the Company cannot assure you that the per share distribution from the Trust Account, if the Company liquidates, will not be less than $10.20, plus interest, due to unforeseen claims of creditors.

Under the DGCL, stockholders may be held liable for claims by third parties against a corporation to the extent of distributions received by them in a dissolution. The pro rata portion of our Trust Account distributed to our public stockholders upon the redemption of 100% of our outstanding public shares in the event we do not complete our initial business combination within the required time period may be considered a liquidation distribution under Delaware law. If the corporation complies with certain procedures set forth in Section 280 of the DGCL intended to ensure that it makes reasonable provision for all claims against it, including a 60-day notice period during which any third-party claims can be brought against the corporation, a 90-day period during which the corporation may reject any claims brought, and an additional 150-day waiting period before any liquidating distributions are made to stockholders, any liability of stockholders with respect to a liquidating distribution is limited to the lesser of such stockholder’s pro rata share of the claim or the amount distributed to the stockholder, and any liability of the stockholder would be barred after the third anniversary of the dissolution.

Because the Company will not be complying with Section 280 of the DGCL as described in our prospectus filed with the SEC on January 18, 2022, Section 281(b) of the DGCL requires us to adopt a plan, based on facts known to us at such time that will provide for our payment of all existing and pending claims or claims that may be potentially brought against us within the 10 years following our dissolution. However, because we are a blank check company, rather than an operating company, and our operations have been limited to searching for prospective target businesses to acquire, the only likely claims to arise would be from our vendors (such as lawyers or investment bankers) or prospective target businesses. If our plan of distribution complies with

Section 281(b) of the DGCL, any liability of stockholders with respect to a liquidating distribution is limited to the lesser of such stockholder’s pro rata share of the claim or the amount distributed to the stockholder, and any liability of the stockholder would likely be barred after the third anniversary of the dissolution. We cannot assure you that we will properly assess all claims that may be potentially brought against us. As such, our stockholders could potentially be liable for any claims to the extent of distributions received by them (but no more) and any liability of our stockholders may extend beyond the third anniversary of such date. Furthermore, if the pro rata portion of our trust account distributed to our public stockholders upon the redemption of our public shares in the event we do not complete our initial business combination within 15 months from the closing of the IPO or during any Extension is not considered a liquidating distribution under Delaware law and such redemption distribution is deemed to be unlawful (potentially due to the imposition of legal proceedings that a party may bring or due to other circumstances that are currently unknown), then pursuant to Section 174 of the DGCL, the statute of limitations for claims of creditors could then be six years after the unlawful redemption distribution, instead of three years, as in the case of a liquidating distribution.

If the Charter Amendment Proposal is approved, the Company, pursuant to the terms of the investment management trust agreement, dated January 13, 2022, by and between the Company and Continental Stock Transfer & Trust Company (the “Trust Agreement”), will (i) remove from the Trust Account an amount, which we refer to as the “Withdrawal Amount,” equal to the number of public shares properly redeemed multiplied by the per-share price, equal to the aggregate amount then on deposit in the Trust Account, including interest not previously released to the Company to pay its franchise and income taxes, divided by the number of then outstanding public shares and (ii) deliver to the holders of such redeemed public shares their portion of the Withdrawal Amount. The remainder of such funds shall remain in the Trust Account and be available for use by the Company to complete a business combination on or before the Extended Date (or Additional Charter Extension Date, if applicable). Holders of public shares who do not redeem their public shares now will retain their redemption rights and their ability to vote on a business combination through the Extended Date (or Additional Charter Extension Date, if applicable) if the Charter Amendment Proposal is approved.

Our Board has fixed the close of business on November 8, 2023 as the date for determining the Company stockholders entitled to receive notice of and vote at the Special Meeting and any adjournment thereof (the “record date”). Only certain holders of record of the Company’s common stock on that date are entitled to have their votes counted at the Special Meeting or any adjournment thereof. On the record date of the Special Meeting, there were 10,935,691 shares of Series A common stock and 1 share of Series B common stock outstanding. Of such shares of common stock, 7,499,999 have agreed not to vote until after the closing of a business combination (which amount represents converted Founder Shares), leaving 3,435,692 shares of Series A common stock and 1 share of Series B common stock eligible to vote at the Special Meeting. The Company’s warrants do not have voting rights in connection with the Charter Amendment Proposal or the Adjournment Proposal.

This Proxy Statement contains important information about the Special Meeting and the proposals. Please read it carefully and vote your shares.

We will pay for the entire cost of soliciting proxies from our working capital. We have engaged Morrow Sodali LLC (the “Proxy Solicitor”) to assist in the solicitation of proxies for the Special Meeting. We have agreed to pay the Proxy Solicitor a fee of $15,000. We will also reimburse the Proxy Solicitor for reasonable out-of-pocket expenses and will indemnify the Proxy Solicitor and its affiliates against certain claims, liabilities, losses, damages and expenses. In addition to these mailed proxy materials, our directors and officers may also solicit proxies in person, by telephone or by other means of communication. These parties will not be paid any additional compensation for soliciting proxies. We may also reimburse brokerage firms, banks and other agents for the cost of forwarding proxy materials to beneficial owners. While the payment of these expenses will reduce the cash available to us to consummate an initial business combination if the Extension to the Extended Date is approved, we do not expect such payments to have a material effect on our ability to consummate an initial business combination.

This Proxy Statement is dated December 1, 2023 and is first being mailed to stockholders on or about December 7, 2023.

TABLE OF CONTENTS

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QUESTIONS AND ANSWERS ABOUT THE SPECIAL MEETING

These Questions and Answers are only summaries of the matters they discuss. They do not contain all of the information that may be important to you. You should read carefully the entire document, including the annexes to this Proxy Statement.

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best efforts, be able to complete a business combination on or before December 19, 2023. If that were to occur, we would be precluded from completing a business combination and would be forced to liquidate even if our stockholders are otherwise in favor of consummating a business combination.

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combination is approved and completed or we have not consummated a business combination by the Termination Date.

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How do I change or revoke my vote?

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1 State Street Plaza, 30th Floor

New York, New York 10004

Attn: SPAC Redemption Team

E-mail: spacredemptions@continentalstock.com

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FORWARD-LOOKING STATEMENTS

Some of the statements contained in this proxy statement constitute forward-looking statements within the meaning of the federal securities laws. Forward-looking statements relate to expectations, beliefs, projections, future plans and strategies, anticipated events or trends and similar expressions concerning matters that are not historical facts. Forward-looking statements reflect our current views with respect to, among other things, any pending business combination, our capital resources and results of operations. Likewise, our financial statements and all of our statements regarding market conditions and results of operations are forward-looking statements. In some cases, you can identify these forward-looking statements by the use of terminology such as “outlook,” “believes,” “expects,” “potential,” “continues,” “may,” “will,” “should,” “could,” “seeks,” “approximately,” “predicts,” “intends,” “plans,” “estimates,” “anticipates” or the negative version of these words or other comparable words or phrases.

The forward-looking statements contained in this proxy statement reflect our current views about future events and are subject to numerous known and unknown risks, uncertainties, assumptions and changes in circumstances that may cause its actual results to differ significantly from those expressed in any forward-looking statement. We do not guarantee that the transactions and events described will happen as described (or that they will happen at all). The following factors, among others, could cause actual results and future events to differ materially from those set forth or contemplated in the forward-looking statements:

While forward-looking statements reflect our good faith beliefs, they are not guarantees of future performance. We disclaim any obligation to publicly update or revise any forward-looking statement to reflect changes in underlying assumptions or factors, new information, data or methods, future events or other changes after the date of this proxy statement, except as required by applicable law. For a further discussion of these and other factors that could cause our future results, performance or transactions to differ significantly from those expressed in any forward-looking statement, please see the section entitled “Risk Factors” below, in our Annual Report on Form 10-K filed with the SEC on April 3, 2023, our Quarterly Reports on Form 10-Q filed with the SEC on May 22, 2023 and August 22, 2023, and in other reports we file with the SEC. You should not place undue reliance on any forward-looking statements, which are based only on information currently available to us (or to third parties making the forward-looking statements).

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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 April 3, 2023, our Quarterly Reports on Form 10-Q filed with the SEC on May 22, 2023 and August 22, 2023, and in the other reports we file with the SEC before making a decision to invest in our securities. 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 Charter Amendment will enable us to complete a business combination.

Approving the Charter Amendment involves a number of risks. Even if an Extension is approved, the Company can provide no assurances that a business combination will be consummated prior to the applicable Termination Date. Our ability to consummate any business combination is dependent on a variety of factors, many of which are beyond our control. If the Extension to the Extended Date is approved, the Company expects to seek shareholder approval of a business combination. Furthermore, the Board, in its discretion, may nevertheless decide to liquidate the Company even prior to the applicable Termination Date if it is in the best interest of our stockholders.

We are required to offer stockholders the opportunity to redeem shares in connection with the Charter Amendment, and we will be required to offer stockholders redemption rights again in connection with any stockholder vote to approve a business combination. Even if an Extension or a business combination are approved by our stockholders, it is possible that redemptions will leave us with insufficient cash to consummate a business combination on commercially acceptable terms, or at all. The fact that we will have separate redemption periods in connection with the Charter Amendment Proposal and a 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.

We entered into a term sheet with Abpro on September 18, 2023, which sets forth the terms and conditions of a potential business combination with Abpro. As of the date of this proxy statement, we are actively negotiating a definitive agreement with Abpro. The term sheet provides for an exclusivity period currently expected to expire sixty days from September 18, 2023. There is no fee or penalty for either party in the event the term sheet is terminated or the contemplated business combination is not consummated. We cannot assure you that we will be able to consummate a business combination or enter into a definitive agreement with Abpro or any other party.

The SEC has recently issued proposed rules relating to certain activities of SPACs. Certain of the procedures that we, a potential business combination target or others may determine to undertake in connection with such proposals may increase our costs and the time needed to complete our initial business combination and may constrain the circumstances under which we could complete an initial business combination. The need for compliance with the SPAC Proposed Rules (defined below) may cause us to liquidate the funds in the Trust Account or liquidate ACAB at an earlier time than we might otherwise choose.

With respect to the regulation of special purpose acquisition companies like the Company (“SPACs”), on March 30, 2022, the SEC issued proposed rules (the “SPAC Proposed Rules”) relating to, among other items, disclosures in business combination transactions involving SPACs and private operating companies; the

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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 to the extent to which SPACs could become subject to regulation under the Investment Company Act of 1940, as amended (the “Investment Company Act”), 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. The SPAC Proposed Rules have not yet been adopted, and may be adopted in the proposed form or in a different form that could impose additional regulatory requirements on SPACs. Certain of the procedures that we, a potential business combination target, or others may determine to undertake in connection with the SPAC Proposed Rules, or pursuant to the SEC’s views expressed in the SPAC Proposed Rules, may increase the costs and time of negotiating and completing an initial business combination, and may constrain the circumstances under which we could complete an initial business combination. The need for compliance with the SPAC Proposed Rules may cause us to liquidate the funds in the Trust Account or liquidate ACAB at an earlier time than we might otherwise choose.

Were we to liquidate, our warrants would expire worthless, and our securityholders would lose the investment opportunity associated with an investment in the combined company, including any potential price appreciation of our securities.

If we are deemed to be an investment company for purposes of the Investment Company Act, we would be required to institute burdensome compliance requirements and our activities would be severely restricted. As a result, in such circumstances, unless we are able to modify our activities so that we would not be deemed an investment company, we would expect to abandon our efforts to complete an initial business combination and instead to liquidate the Company.

As described further above, the SPAC Proposed Rules relate, among other matters, to the circumstances in which SPACs such as the Company could potentially be subject to the Investment Company Act and the regulations thereunder. The SPAC Proposed Rules would provide a safe harbor for such companies from the definition of “investment company” under Section 3(a)(1)(A) of the Investment Company Act, provided that a SPAC satisfies certain criteria, including a limited time period to announce and complete a de-SPAC transaction. Specifically, to comply with the safe harbor, the SPAC Proposed Rules would require a company to file a report on Form 8-K announcing that it has entered into an agreement with a target company for a business combination no later than 18 months after the effective date of its registration statement for its initial public offering (the “IPO Registration Statement”). The company would then be required to complete its initial business combination no later than 24 months after the effective date of the IPO Registration Statement.

If we are deemed to be an investment company under the Investment Company Act, our activities would be severely restricted. In addition, we would be subject to burdensome compliance requirements. We do not believe that our principal activities will subject us to regulation as an investment company under the Investment Company Act. However, if we are deemed to be an investment company and subject to compliance with and regulation under the Investment Company Act, we would be subject to additional regulatory burdens and expenses for which we have not allotted funds. As a result, unless we are able to modify our activities so that we would not be deemed an investment company, we would expect to abandon our efforts to complete an initial business combination and instead to liquidate the Company. Were we to liquidate, our warrants would expire worthless, and our securityholders would lose the investment opportunity associated with an investment in the combined company, including any potential price appreciation of our securities.

To mitigate the risk of us being deemed to have been operating as an unregistered investment company (including under the subjective test of Section 3(a)(1)(A) of the Investment Company Act), on or prior to the 24-month anniversary of the effective date of our registration statement relating to our initial public offering, we will instruct the Trustee with respect to the Trust Account, to liquidate the U.S. government securities or money market funds held in the Trust Account and thereafter to hold all funds in the Trust Account in cash

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(which may include demand deposit accounts) until the earlier of the consummation of our business combination or liquidation. As a result, we will likely receive minimal interest on the funds held in the Trust Account, which would reduce the dollar amount our public stockholders would receive upon any redemption or liquidation of the Company. Currently, all funds in the Trust Account are held in U.S. government securities or money market funds. The longer the funds in the Trust Account are held in such U.S. government securities or money market funds, the greater the risk that the Company will be deemed to be an unregistered investment company under the Investment Company Act.

The funds in the Trust Account are held only in U.S. government treasury obligations with a maturity of 185 days or less or in money market funds investing solely in U.S. government treasury obligations and meeting certain conditions under Rule 2a-7 under the Investment Company Act. However, to mitigate the risk of us being deemed to be an unregistered investment company (including under the subjective test of Section 3(a)(1)(A) of the Investment Company Act) and thus subject to regulation under the Investment Company Act, on or prior to the 24-month anniversary of the effective date of our registration statement relating to the initial public offering, we intend to instruct Continental Stock Transfer & Trust Company, the trustee with respect to the Trust Account, to liquidate the U.S. government treasury obligations or money market funds held in the Trust Account and thereafter to maintain the funds in a bank demand deposit account until the earlier of the consummation of our initial business combination or liquidation of the Company. We will likely receive minimal interest on the funds held in the Trust Account. However, interest previously earned on the funds held in the Trust Account still may be released to us to pay our taxes, if any, and certain other expenses as permitted. As a result, the decision to liquidate the securities held in the Trust Account and thereafter to hold all funds in a bank demand deposit account would reduce the dollar amount our public stockholders would receive upon any redemption or liquidation of the Company. Currently, all funds in the Trust Account are held in U.S. government securities or money market funds. The longer the funds in the Trust Account are held in such U.S. government securities or money market funds, the greater the risk that the Company will be deemed to be an unregistered investment company under the Investment Company Act.

We have identified ineffective disclosure controls and procedures that, if unsuccessfully remediated, could adversely affect our ability to report our financial results on a timely and accurate basis and to consummate an initial business combination.

Under the supervision and with the participation of our management, including our principal executive officer and principal financial officer, we conducted an evaluation of the effectiveness of our disclosure controls and procedures. Based on such evaluation, our principal executive officer and principal financial officer have concluded that our disclosure controls and procedures were not effective as of September 30, 2023 due to the Company not filing timely tax returns and utilizing cash withdrawn from the Trust Account for tax obligations for operating purposes. Failure to achieve and maintain effective disclosure controls and procedures could adversely affect our ability to report our financial results on a timely and accurate basis and to consummate an initial business combination. We may also identify material weaknesses or other deficiencies in our disclosure controls and procedures in the future. Any material weaknesses or other deficiencies in our control systems may affect our ability to comply with SEC reporting requirements and listing standards or cause our financial statements to contain material misstatements which could negatively affect market price and trading liquidity of our common stock.

Since the 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 Company’s warrants, which will expire worthless in the event of our winding up. In the event of a liquidation, our Sponsor will not receive any monies held in the Trust Account as a result of its ownership of 7,200,000 Founder Shares and 13,850,000 Private Placement Warrants that were purchased by the Sponsor in a private placement which occurred

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simultaneously with the completion of the IPO. As a consequence, a liquidating distribution will be made only with respect to the public shares. In addition, each of our independent directors and an advisor to us owns 50,000 Founder Shares. Such persons have waived their rights to liquidating distributions from the Trust Account with respect to these securities, and 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 common stock experience a negative rate of return, due to having initially purchased the Founder Shares for an aggregate of $25,000. Our Sponsor, directors and officers may therefore have interests different from, or in addition to, your interests as a stockholder in connection with the proposals at the Special Meeting.

A new 1% U.S. federal excise tax could be imposed on us in connection with redemptions by us of our shares.

On August 16, 2022, the Inflation Reduction Act of 2022 (the “IRA”) was signed into federal law. The IRA provides for, among other things, a new U.S. federal 1% excise tax on certain repurchases (including redemptions) of stock by publicly traded domestic (i.e., U.S.) corporations and certain domestic subsidiaries of publicly traded foreign corporations. The excise tax is imposed on the repurchasing corporation itself, not its stockholders from which shares are repurchased. The amount of the excise tax is generally 1% of the fair market value of the shares repurchased at the time of the repurchase. However, for purposes of calculating the excise tax, repurchasing corporations are permitted to net the fair market value of certain new stock issuances against the fair market value of stock repurchases during the same taxable year. In addition, certain exceptions apply to the 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 the excise tax. IRS and Treasury have issued a notice of an intention to issue proposed regulations (the “Notice”); the Notice also provides interim guidance on which taxpayers can rely until issuance of the proposed regulations.

The IRA excise tax applies only to repurchases that occur after December 31, 2022. It is uncertain whether, and/or to what extent, the excise tax could apply to any redemptions of our public shares after December 31, 2022, including any redemptions in connection with initial business combination or extension requests, or exchanges of stock pursuant to an acquisitive reorganization (i.e., pursuant to the initial business combination or otherwise). The Company confirms that amounts placed in the Trust Account in connection with the IPO, as well as any interest earned thereon, will not be used to pay for the excise tax. Under the Notice distributions pursuant to a complete liquidation of the Company (e.g., in the event we do not consummate an initial business combination) generally are not subject to this 1% excise tax, and other redemptions or repurchases of stock made during the same taxable year as the taxable year the Company completely liquidates and dissolves also would be exempt. Any redemption or other repurchase that occurs after December 31, 2022, in connection with a business combination, extension request or otherwise may be subject to the excise tax. Whether and to what extent we would be subject to the excise tax in connection with a business combination or otherwise would depend on a number of factors, including (i) the fair market value of the stock subject to redemptions and repurchases or exchanged in an acquisitive reorganization in connection with the business combination, (ii) the structure of the business combination, (iii) the nature and amount of any private investment in public equity or other equity issuances in connection with the business combination (or otherwise issued not in connection with the business combination but issued within the same taxable year of the business combination) and (iv) the content of regulations and other guidance from the Treasury. In addition, because the excise tax would be payable by us, and not by the redeeming holder, the mechanics of any required payment of the excise tax have not been determined. The foregoing could cause a reduction in the cash available on hand to complete a business combination and in our ability to complete a business combination, and might affect the structure chosen for a business combination and any potential financing in connection with the business combination.

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We may be deemed a “foreign person” under the regulations relating to the Committee on Foreign Investment in the United States (“CFIUS”), and any business combination may be subject to U.S. foreign investment regulations and review by CFIUS or another U.S. government entity.

Our sponsor, Atlantic Coastal Acquisition Management II LLC, is controlled by and has substantial ties with a non-U.S. person given that the managing member of our sponsor is a citizen of the Republic of Cyprus. Certain federally licensed businesses in the United States are subject to rules or regulations that limit foreign ownership. In addition, CFIUS is an interagency committee authorized to review certain transactions involving “foreign persons” to determine the effect of such transactions on U.S. national security. Therefore, because we may be considered a “foreign person” under such rules and regulations, we could be subject to foreign ownership restrictions and/or CFIUS review if our proposed business combination is between us and a U.S. target company engaged in a regulated industry or which may affect national security.

The scope of CFIUS was expanded by the Foreign Investment Risk Review Modernization Act of 2018 (“FIRRMA”) to include certain non-passive, non-controlling investments in sensitive U.S. businesses. FIRRMA, and subsequent implementing regulations that are now in force, also subject certain categories of investments to mandatory CFIUS filings. It is unclear at this stage whether our potential business combination will fall within CFIUS’s jurisdiction, and if so, whether we would be required to make a mandatory filing or determine to submit a voluntary notice to CFIUS. If we seek CFIUS review prior to the completion of our initial business combination, we may be subject to substantial delays and increased transaction costs. If we are required to undergo a CFIUS review following the completion of our initial business combination, in addition to any conditions or divestiture requirements imposed on us, we may incur substantial costs in connection therewith. Other possible foreign ownership limitations, and the potential impact of CFIUS, may limit the attractiveness of a transaction with us or prevent us from pursuing certain initial business combination opportunities that we believe would otherwise be beneficial to us and our shareholders. As a result, the pool of potential targets with which we could complete an initial business combination may be limited and we may be adversely affected in terms of competing with other special purpose acquisition companies which do not have similar foreign ownership issues.

Moreover, the process of government review, whether by CFIUS or otherwise, could be lengthy and we have limited time to complete our initial business combination. If we cannot complete our initial business combination within the applicable Termination Date because the review process drags on beyond such timeframe or because our initial business combination is ultimately prohibited by CFIUS or another U.S. government entity, we may be required to liquidate. If we liquidate, our public stockholders may only receive $10.20 per share of Series A common stock on the liquidation of their shares and our warrants will expire worthless. This will also cause our investors to lose the investment opportunity in a target company and the chance of realizing future gains on your investment through any price appreciation in the combined company.

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BACKGROUND

We are a blank check company formed in Delaware on May 21, 2021, for the purpose of effecting a merger, capital stock exchange, asset acquisition, stock purchase, reorganization or similar business combination with one or more businesses.

There are currently 10,935,691 shares of Series A common stock and 1 share of Series B common stock issued and outstanding. In addition, we issued warrants to purchase 15,000,000 shares of our Series A common stock as part of the units offered in our IPO, along with an aggregate of 13,850,000 warrants (convertible into an aggregate of 13,850,000 shares of Series A common stock) underlying the private placement warrants issued to our Sponsor in a private placement simultaneously with the consummation of our IPO, and we issued 15,000,000 public warrants. Each whole warrant entitles its holder to purchase one whole share of Series A common stock at an exercise price of $11.50 per share. The warrants will become exercisable until the later of 30 days after the completion of our initial business combination and 12 months from the closing of our IPO and expire five years after the completion of our initial business combination or earlier upon redemption or liquidation. We have the ability upon a minimum of 30 days’ prior written notice (the “redemption period”) to redeem outstanding warrants at any time after they become exercisable and prior to their expiration, at a price of $0.01 per warrant, provided that the reported last sale price of our Series A common stock equals or exceeds $18.00 per share (as adjusted for stock splits, stock dividends, reorganizations, recapitalizations and the like and certain issuances of Series A common stock and equity-linked securities) for any 20 trading days within a 30 trading-day period commencing once the warrants become exercisable and ending on the third trading day prior to the date on which we give proper notice of such redemption and provided certain other conditions are met.

In addition, if (x) the Company issues additional Series A common stock or equity-linked securities for capital raising purposes in connection with the closing of a business combination at an issue price or effective issue price of less than $9.20 per Series A common stock (with such issue price or effective issue price to be determined in good faith by the Company’s board of directors and, in the case of any such issuance to the Sponsor or its affiliates, without taking into account any Founder Shares held by the Sponsor or its affiliates, as applicable, prior to such issuance) (the “Newly Issued Price”), (y) the aggregate gross proceeds from such issuances represent more than 60% of the total equity proceeds, and interest thereon, available for the funding of a business combination on the date of the consummation of a business combination (net of redemptions), and (z) the volume weighted average trading price of its Series A common stock during the 20 trading day period starting on the trading day prior to the day on which the Company consummates its business combination (such price, the “Market Value”) is below $9.20 per share, the exercise price of the warrants will be adjusted (to the nearest cent) to be equal to 115% of the higher of the Market Value and the Newly Issued Price, and the $18.00 per share redemption trigger price will be adjusted (to the nearest cent) to be equal to 180% of the higher of the Market Value and the Newly Issued Price.

A total of $306,000,000 of the proceeds from our IPO and the simultaneous sale of the Private Placement Warrants in a private placement transaction was placed in our Trust Account in the United States maintained by Continental Stock Transfer & Trust Company, acting as trustee, invested in U.S. “government securities,” within the meaning of Section 2(a)(16) of the Investment Company Act, with a maturity of 185 days or less or in any open ended investment company that holds itself out as a money market fund selected by us meeting the conditions of Rule 2a-7 of the Investment Company Act, until the earlier of: (i) the consummation of a business combination or (ii) the distribution of the proceeds in the Trust Account as described below.

On April 18, 2023, we held a special meeting (the “April Meeting”) pursuant to which our stockholders approved and we filed an Amendment to our Amended and Restated Certificate of Incorporation to extend the Termination Date from April 19, 2023 to the Original Termination Date. In connection with the April Meeting, holders of an aggregate 26,564,308 public shares exercised, and did not reverse, their right to redeem their public shares. In addition, holders of Founder Shares agreed to convert all but one of their Founder Shares from Series B common stock into Series A common stock. Such holders agreed that such newly converted Founder Shares would not have redemption rights and would not be voted until the closing of a business combination.

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Approximately $36.7 million was held in the Trust Account as of the record date. The mailing address of the Company’s principal executive office is 6 St Johns Lane, Floor 5 New York, NY 10013.

You are not being asked to vote on a business combination at this time. If the Extension to the Extended Date is implemented and you do not elect to redeem your public shares, provided that you are a stockholder on the record date for a meeting to consider a business combination, you will retain the right to vote on a business combination when it is submitted to stockholders and the right to redeem your public shares for cash in the event a business combination is approved and completed or we have not consummated a business combination by the applicable Termination Date.

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THE CHARTER AMENDMENT PROPOSAL

The Company is proposing to amend its charter to extend the date by which we must consummate a business combination.

The sole purpose of the Charter Amendment Proposal is to allow the Company more time to complete a business combination.

We are actively searching for potential business combination opportunities. In the event that we enter into a definitive agreement for an initial business combination prior to the Special Meeting, we will issue a press release and file a Current Report on Form 8-K with the SEC announcing a proposed business combination.

If the Charter Amendment Proposal is not approved, we will not redeem any shares in respect of which public stockholders have made an Election, and will, as promptly as reasonably practicable, and in any event within 5 business days, return any shares tendered to the Company’s transfer agent prior to the Special Meeting. Further, if the Charter Amendment is not approved and we do not consummate a business combination by December 19, 2023, in accordance with our charter, we 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, redeem 100% of the public shares, at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account, including interest earned and not previously released to the Company to pay its taxes, if any (less taxes payable and up to $100,000 of such net interest to pay dissolution expenses), divided by the number of then issued and outstanding public shares, which redemption will completely extinguish the rights of the Public Stockholders (as defined in the charter) as 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 Company’s remaining stockholders and the Company’s board of directors, dissolve and liquidate, subject (in the case of (ii) and (iii) above) to the Company’s obligations under the DGCL to provide for claims of creditors and other requirements of applicable law.

We reserve the right at any time to cancel the Special Meeting and not to submit to our stockholders the Charter Amendment Proposal and implement the Charter Amendment. In the event the Special Meeting is cancelled, we may dissolve and liquidate in accordance with the charter.

The Board believes that given our expenditure of time, effort and money on searching for potential business combination opportunities, circumstances warrant providing public stockholders an opportunity to consider a business combination and that it is in the best interests of our stockholders that we obtain an Extension.

A copy of the proposed amendment to the charter of the Company is attached to this Proxy Statement in Annex A.

Reasons for the Charter Amendment Proposal

The Company’s charter provides that the Company has until December 19, 2023 to complete the purposes of the Company including, but not limited to, effecting a business combination under its terms. The purpose of the proposed Extension is to allow the Company more time to complete its initial business combination.

If the Charter Amendment Proposal is approved and the Charter Amendment becomes effective, the Sponsor will deposit the lesser of (a) $30,000 or (b) $0.045 for each public share that is not redeemed in connection with the Special Meeting. In the event that ACAB has not consummated a business combination by the Extended Date, without approval of the holders of ACAB’s public shares, ACAB may, by resolution of the Board, if requested by the Sponsor, and upon five days’ advance notice prior to the applicable Termination Date, extend the Termination Date up to six times, each by one additional month (for a total of up to nine additional months to complete a business combination), provided that the Payor will deposit into the Trust Account: for

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each such monthly extension, the lesser of (a) $10,000 or (b) $0.015 for each public share that is not redeemed in connection with the Special Meeting for an aggregate deposit of up to the lesser of (x) $60,000 or (y) $0.09 for each public share that is not redeemed in connection with the Special Meeting (if all six additional monthly extensions are exercised). For illustrative purposes, if the Charter Amendment Proposal is approved and ACAB takes the maximum time to complete a business combination through the exercise of each Extension available to the Board and the Sponsor, the redemption price per share at the meeting for such business combination or ACAB’s subsequent liquidation would be approximately $10.71 per public share, based on the aggregate amount on deposit in the Trust Account of approximately $36.7 million as of November 8, 2023, and an aggregate of $90,000 to be deposited by the Payor, divided by the total number of then outstanding public shares (assuming no public stock is redeemed in connection with the Special Meeting, and not giving effect to the accrual of any further interest or any interest to be released to ACAB to pay its franchise and income taxes), in comparison to the redemption price as of December 15, 2023 of approximately $10.68 per share.

We entered into a term sheet with Abpro, a biotechnology company, on September 18, 2023, which sets forth the terms and conditions of a potential business combination with Abpro. As of the date of this proxy statement, we are actively negotiating a definitive agreement with Abpro. The term sheet provides for an exclusivity period currently expected to expire sixty days from September 18, 2023. There is no fee or penalty for either party in the event the term sheet is terminated or the contemplated business combination is not consummated. While we are using our best efforts to complete a business combination as soon as practicable, the Board believes that there will not be sufficient time before the Original Termination Date to complete a business combination with Abpro or any other party. Accordingly, the Board believes that in order to be able to consummate a business combination, we will need to obtain an Extension. Without an Extension, the Board believes that there is significant risk that we might not, despite our best efforts, be able to complete a business combination on or before December 19, 2023. If that were to occur, we would be precluded from completing a business combination and would be forced to liquidate even if our stockholders are otherwise in favor of consummating a business combination.

If the Extension to the Extended Date is approved and implemented, we intend to complete a business combination as soon as possible and in any event on or before the applicable Termination Date.

The Company’s charter provides that the affirmative vote of the holders of at least 65% of all outstanding shares of common stock entitled to vote on the matter is required to extend our corporate existence, except in connection with, and effective upon, consummation of a business combination. Additionally, our IPO prospectus and charter 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 a business combination would be in the best interests of our stockholders, and because we will not be able to conclude a 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 December 19, 2023 to the Extended Date. We intend to hold another stockholder meeting prior to the Extended Date (or Additional Charter Extension Date, if applicable) in order to seek stockholder approval of a business combination.

We believe that the foregoing charter provision was included to protect Company stockholders from having to sustain their investments for an unreasonably long period if the Company failed to find a suitable business combination in the timeframe contemplated by the charter. We also believe that, given the Company’s expenditure of time, effort and money on searching for potential business combination opportunities, circumstances warrant providing public stockholders an opportunity to consider a business combination.

If the Charter Amendment Proposal is Not Approved

Stockholder approval of the Charter Amendment is required for the implementation of our Board’s plan to extend the date by which we must consummate our initial business combination. Therefore, our Board will

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abandon and not implement the Charter Amendment unless our stockholders approve the Charter Amendment Proposal.

If the Charter Amendment Proposal is not approved, we will not redeem any shares in respect of which public stockholders have made an Election, and will, as promptly as reasonably practicable, and in any event within 5 business days, return any shares tendered to the Company’s transfer agent prior to the Special Meeting. Further, if the Charter Amendment is not approved and we do not consummate a business combination by December 19, 2023, in accordance with our charter, we 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, redeem 100% of the public shares, at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account, including interest earned and not previously released to the Company to pay its taxes, if any (less taxes payable and up to $100,000 of such net interest to pay dissolution expenses), divided by the number of then issued and outstanding public shares, which redemption will completely extinguish the rights of the Public Stockholders (as defined in the charter) as 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 Company’s remaining stockholders and the Company’s board of directors, dissolve and liquidate, subject (in the case of (ii) and (iii) above) to the Company’s obligations under the DGCL to provide for claims of creditors and other requirements of applicable law.

There will be no distribution from the Trust Account with respect to the Company’s warrants which will expire worthless in the event we wind up. In the event of a liquidation, our Sponsor, directors and officers will not receive any monies held in the Trust Account as a result of their ownership of the Founder Shares, the Private Placement Warrants or any Series A common stock issued in connection with the conversion of the Founder Shares.

If the Charter Amendment Proposal Is Approved

If the Charter Amendment Proposal is approved, the Company will 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 to extend the time it has to complete a business combination until the Extended Date (or Additional Charter Extension Date, if applicable). The Company will remain a reporting company under the Exchange Act and its units, Series A common stock and public warrants will remain publicly traded. The Company will then continue to work to consummate a business combination by the Extended Date (or Additional Charter Extension Date, if applicable).

Notwithstanding stockholder approval of the Charter Amendment Proposal, our Board will retain the right to abandon and not implement the Extension to the Extended Date at any time without any further action by our stockholders. We reserve the right at any time to cancel the Special Meeting and not to submit to our stockholders the Charter Amendment Proposal and implement the Charter Amendment. In the event the Special Meeting is cancelled, we may dissolve and liquidate in accordance with the charter. Furthermore, the Board, in its discretion, may nevertheless decide to liquidate the Company even prior to the applicable Termination Date if it is in the best interest of our stockholders.

You are not being asked to vote on a business combination at this time. If the Extension to the Extended Date is implemented and you do not elect to redeem your public shares, provided that you are a stockholder on the record date for a meeting to consider a business combination, you will retain the right to vote on a business combination when it is submitted to stockholders and the right to redeem your public shares for cash in the event a business combination is approved and completed or we have not consummated a business combination by the applicable Termination Date.

If the Charter Amendment Proposal is approved, and the Extension to the Extended Date 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

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if the Charter Amendment Proposal is approved, and the amount remaining in the Trust Account may be only a small fraction of the approximately $36.7 million held in the Trust Account as of the record date. We will not proceed with the Extension to the Extended Date if redemptions or repurchases of our public shares cause us to have less than $5,000,001 of net tangible assets following approval of the Charter Amendment Proposal.

Redemption Rights

If the Charter Amendment Proposal is approved, and the Extension to the Extended Date is implemented, each public stockholder may seek to redeem its public shares at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account, including interest (which interest shall be net of taxes payable), divided by the number of then outstanding public shares. Holders of public shares who do not elect to redeem their public shares in connection with the Extension to the Extended Date will retain the right to redeem their public shares in connection with any stockholder vote to approve a proposed business combination, or if the Company has not consummated a business combination by the applicable Termination Date.

TO EXERCISE YOUR REDEMPTION RIGHTS, YOU MUST SUBMIT A REQUEST IN WRITING THAT WE REDEEM YOUR PUBLIC SHARES FOR CASH TO CONTINENTAL STOCK TRANSFER & TRUST COMPANY AT THE ADDRESS BELOW, AND, AT THE SAME TIME, ENSURE YOUR BANK OR BROKER COMPLIES WITH THE REQUIREMENTS IDENTIFIED ELSEWHERE HEREIN, INCLUDING DELIVERING YOUR SHARES TO THE TRANSFER AGENT PRIOR TO THE VOTE ON THE CHARTER AMENDMENT PROPOSAL PRIOR TO 5:00 P.M. EASTERN TIME ON DECEMBER 13, 2023. THE REDEMPTION RIGHTS INCLUDE THE REQUIREMENT THAT A STOCKHOLDER MUST IDENTIFY ITSELF IN WRITING AS A BENEFICIAL HOLDER AND PROVIDE ITS LEGAL NAME, PHONE NUMBER AND ADDRESS IN ORDER TO VALIDLY REDEEM ITS PUBLIC SHARES.

In connection with tendering your shares for redemption, prior to 5:00 p.m. Eastern Time on December 13, 2023 (two business days before the Special Meeting), you must elect either to physically tender your stock certificates to Continental Stock Transfer & Trust Company, 1 State Street Plaza, 30th Floor, New York, New York 10004, Attn: SPAC Redemption Team, or to deliver your shares to the transfer agent 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 December 13, 2023 (two business days before the Special Meeting) ensures that a redeeming holder’s election is irrevocable once the Charter 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 stockholder, whether or not it is a record holder or its shares are held in “street name,” by contacting the transfer agent 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 stock 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. The transfer agent 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 stock 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.

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Certificates that have not been tendered in accordance with these procedures prior to 5:00 p.m. Eastern Time on December 13, 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 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 Charter 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 Charter Amendment Proposal will not be approved. The Company anticipates that a public stockholder who tenders shares for redemption in connection with the vote to approve the Charter Amendment Proposal would receive payment of the redemption price for such shares soon after the completion of the Charter Amendment. 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 properly demanded, the Company will redeem each public share for a per-share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account, including interest (which interest shall be net of taxes payable), divided by the number of then outstanding public shares. Based upon the current amount in the Trust Account, the Company anticipates that the per-share price at which public shares will be redeemed from cash held in the Trust Account will be approximately $10.68 at the time of the Special Meeting. The closing price of the Company’s Series A common stock on November 30, 2023, the most recent practicable date prior to the date of this proxy statement, was $10.60.

If you exercise your redemption rights, you will be exchanging your shares of the Company’s Series A common stock 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 December 13, 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 Charter Amendment Proposal would receive payment of the redemption price for such shares soon after the completion of the Extension to the Extended Date.

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UNITED STATES FEDERAL INCOME TAX CONSIDERATIONS

The following is a discussion of certain material U.S. federal income tax considerations for holders of our Series A common stock with respect to the exercise of redemption rights in connection with the approval of the Charter Amendment Proposal. This discussion is limited to certain U.S. federal income tax considerations to beneficial owners of our Series A common stock who hold such stock as a capital asset within the meaning of Section 1221 of the U.S. Internal Revenue Code of 1986, as amended (the “Code”).

This discussion is a summary only and does not describe all of the tax consequences that may be relevant to you in light of your particular circumstances, including but not limited to the alternative minimum tax, the Medicare tax on certain net investment income and the different consequences that may apply if you are subject to special rules that apply to certain types of investors, including but not limited to:

If a partnership (including an entity or arrangement treated as a partnership for U.S. federal income tax purposes) or other pass-through entity holds our Series A common stock, the U.S. federal income tax treatment of a partner in such partnership or equityholder in such pass-through entity generally will depend upon the status of the partner or equityholder, upon the activities of the partnership or other pass-through entity and upon certain determinations made at the partner or equityholder level. Accordingly, we urge partners in partnerships (including entities or arrangements treated as partnerships for U.S. federal income tax purposes) and equityholders in other pass-through entities considering the purchase of our Series A common stock to consult their tax advisors regarding the U.S. federal income tax considerations of the purchase, ownership and disposition of our securities by such partnership or pass-through entity.

This discussion is based on the Code, and administrative pronouncements, judicial decisions and final, temporary and proposed Treasury regulations as of the date hereof, which are subject to change, possibly on a

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retroactive basis, and changes to any of which subsequent to the date of this prospectus may affect the tax consequences described herein. This discussion does not address any aspect of state, local or non-U.S. taxation, or any U.S. federal taxes other than income taxes (such as gift and estate taxes).

We have not sought, and will not seek, a ruling from the U.S. Internal Revenue Service (the “IRS”) as to any U.S. federal income tax consequence described herein. The IRS may disagree with the discussion herein, and its determination may be upheld by a court. Moreover, there can be no assurance that future legislation, regulations, administrative rulings or court decisions will not adversely affect the accuracy of the statements in this discussion. You are urged to consult your tax advisor with respect to the application of U.S. federal tax laws to your particular situation, as well as any tax consequences arising under the laws of any state, local or foreign jurisdiction.

WE URGE HOLDERS OF OUR SERIES A COMMON STOCK CONTEMPLATING EXERCISE OF THEIR REDEMPTION RIGHTS TO CONSULT THEIR OWN TAX ADVISORS CONCERNING THE UNITED STATES FEDERAL, STATE, LOCAL, AND FOREIGN AND OTHER TAX CONSEQUENCES THEREOF.

U.S. Federal Income Tax Considerations to U.S. Holders

This section is addressed to U.S. Holders of our Series A common stock that elect to have their Series A common stock of the Company redeemed for cash. For purposes of this discussion, a “U.S. Holder” is a beneficial owner who or that is, for U.S. federal income tax purposes:

Redemption of Series A Common Stock

In the event that a U.S. Holder’s Series A common stock is redeemed, the treatment of the transaction for U.S. federal income tax purposes will depend on whether the redemption qualifies as a sale of the Series A common stock under Section 302 of the Code. Whether the redemption qualifies for sale treatment will depend largely on the total number of shares of our stock treated as held by the U.S. Holder (including any stock constructively owned by the U.S. Holder as a result of owning warrants) relative to all of our shares both before and after the redemption. The redemption of Series A common stock generally will be treated as a sale of the Series A common stock (rather than as a corporate distribution) if the redemption (i) is “substantially disproportionate” with respect to the U.S. Holder, (ii) results in a “complete termination” of the U.S. Holder’s interest in us or (iii) is “not essentially equivalent to a dividend” with respect to the U.S. Holder. These tests are explained more fully below.

In determining whether any of the foregoing tests are satisfied, a U.S. Holder takes into account not only stock actually owned by the U.S. Holder, but also shares of our stock that are constructively owned by it. A U.S. Holder may constructively own, in addition to stock owned directly, stock owned by certain related individuals and entities in which the U.S. Holder has an interest or that have an interest in such U.S. Holder, as well as any stock the U.S. Holder has a right to acquire by exercise of an option, which would generally include Series A

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common stock which could be acquired pursuant to the exercise of the warrants. In order to meet the substantially disproportionate test, the percentage of our outstanding voting stock actually and constructively owned by the U.S. Holder immediately following the redemption of Series A common stock must, among other requirements, be less than 80% of our outstanding voting stock actually and constructively owned by the U.S. Holder immediately before the redemption. There will be a complete termination of a U.S. Holder’s interest if either (i) all of the shares of our stock actually and constructively owned by the U.S. Holder are redeemed or (ii) all of the shares of our stock actually owned by the U.S. Holder are redeemed and the U.S. Holder is eligible to waive, and effectively waives in accordance with specific rules, the attribution of stock owned by certain family members and the U.S. Holder does not constructively own any other stock. The redemption of the Series A common stock will not be essentially equivalent to a dividend if a U.S. Holder’s conversion results in a “meaningful reduction” of the U.S. Holder’s proportionate interest in us. Whether the redemption will result in a meaningful reduction in a U.S. Holder’s proportionate interest in us will depend on the 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.”

If none of the foregoing tests are satisfied, then the redemption will be treated as a corporate distribution and the tax effects will be as described below under “U.S. Federal Income Tax Considerations to U.S. Holders — Taxation of Distributions.” After the application of those rules, any remaining tax basis of the U.S. holder in the redeemed Series A common stock will be added to the U.S. holder’s adjusted tax basis in its remaining stock, or, if it has none, to the U.S. holder’s adjusted tax basis in its warrants or possibly in other stock constructively owned by it.

U.S. Holders of our Series A common stock considering exercising their redemption rights should consult their own tax advisors as to whether the redemption of their Series A common stock of the Company will be treated as a sale or as a distribution under the Code.

Gain or Loss on a Redemption of Series A Common Stock Treated as a Sale

If the redemption qualifies as a sale of Series A common stock, a U.S. Holder must treat any gain or loss recognized as capital gain or loss. Any such capital gain or loss will be long-term capital gain or loss if the U.S. Holder’s holding period for the Series A common stock so disposed of exceeds one year. It is unclear, however, whether the redemption rights with respect to the Series A common stock may suspend the running of the applicable holding period for this purpose. If the running of the holding period for the Series A common stock is suspended, then non-corporate U.S. holders may not be able to satisfy the one-year holding period requirement for long-term capital gain treatment, in which case any gain on a sale or taxable disposition of the Series A common stock would be subject to short-term capital gain treatment and would be taxed at regular ordinary income tax rates. Generally, a U.S. Holder will recognize gain or loss in an amount equal to the difference between (i) the amount of cash received in such redemption (or, if the Series A common stock is held as part of a unit at the time of the disposition, the portion of the amount realized on such disposition that is allocated to the Series A common stock based upon the then fair market values of the Series A common stock and the one-half of one warrant included in the unit) and (ii) the U.S. Holder’s adjusted tax basis in its Series A common stock so redeemed. A U.S. Holder’s adjusted tax basis in its Series A common stock generally will equal the U.S. Holder’s acquisition cost (that is, the portion of the purchase price of a unit allocated to a share of Series A common stock or the U.S. Holder’s initial basis for Series A common stock upon exercise of a whole warrant) less any prior distributions treated as a return of capital. Long-term capital gains realized by a non-corporate U.S. Holder generally will be taxable at a reduced rate. The deductibility of capital losses is subject to limitations.

Taxation of Distributions

If the redemption does not qualify as a sale of Series A common stock, the U.S. Holder will be treated as receiving a distribution. In general, any distributions to U.S. Holders generally will constitute dividends for

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United States federal income tax purposes to the extent paid from our current or accumulated earnings and profits, as determined under United States 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) the U.S. Holder’s adjusted tax basis in our Series A common stock. Any remaining excess will be treated as gain realized on the sale or other disposition of the Series A common stock and will be treated as described under “U.S. Federal Income Tax Considerations to U.S. Holders — Gain or Loss on a Redemption of Series A Common Stock Treated as a Sale.” Dividends we pay to a U.S. Holder that is a taxable corporation generally will qualify for the dividends received deduction if the requisite holding period is satisfied. With certain exceptions (including, but not limited to, dividends treated as investment income for purposes of investment interest deduction limitations), and provided certain holding period requirements are met, dividends we pay to a non- corporate U.S. Holder generally will constitute “qualified dividends” that will be subject to tax at preferential long-term capital gains rates. It is unclear whether the redemption rights prior to our initial business combination with respect to the Series A common stock may prevent a U.S. holder 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. If the holding period requirements are not satisfied, then a corporation may not be able to qualify for the dividends received deduction and would have taxable income equal to the entire dividend amount, and non-corporate holders may be subject to tax on such dividend at regular ordinary income tax rates instead of the preferential rate that applies to qualified dividend income.

U.S. Federal Income Tax Considerations to Non-U.S. Holders

This section is addressed to Non-U.S. Holders of our Series A common stock that elect to have their Series A common stock of the Company redeemed for cash. For purposes of this discussion, a “Non-U.S. Holder” is a beneficial owner who or that is for U.S. federal income tax purposes:

but generally does not include an individual who is present in the United States for 183 days or more in the taxable year of disposition. If you are such an individual, you should consult your tax advisor regarding the U.S. federal income tax consequences of the acquisition, ownership or sale or other disposition of our securities.

Redemption of Series A Common Stock

The characterization for United States federal income tax purposes of the redemption of a Non-U.S. Holder’s Series A common stock generally will correspond to the United States federal income tax characterization of such a redemption of a U.S. Holder’s Series A common stock, as described under “U.S. Federal Income Tax Considerations to U.S. Holders.”

Non-U.S. Holders of our Series A common stock considering exercising their redemption rights should consult their own tax advisors as to whether the redemption of their Series A common stock of the Company will be treated as a sale or as a distribution under the Code.

Gain or Loss on a Redemption of Series A Common Stock Treated as a Sale

If the redemption qualifies as a sale of Series A common stock, a Non-U.S. Holder generally will not be subject to United States federal income or withholding tax in respect of gain recognized on a sale of its Series A common stock of the Company, unless:

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Unless an applicable treaty provides otherwise, gain described in the first bullet point above will be subject to tax at generally applicable U.S. federal income tax rates as if the Non-U.S. holder were a United States resident. Any gains described in the first bullet point above of a Non-U.S. holder that is a foreign corporation may also be subject to an additional “branch profits tax” at a thirty percent rate (or lower treaty rate).

Taxation of Distributions

If the redemption does not qualify as a sale of Series A common stock, the Non-U.S. Holder will be treated as receiving a distribution. In general, any distributions we make to a Non-U.S. Holder of shares of our Series A common stock, to the extent paid out of our current or accumulated earnings and profits (as determined under United States federal income tax principles), will constitute dividends for U.S. federal income tax purposes and, provided such dividends are not effectively connected with the Non-U.S. Holder’s conduct of a trade or business within the United States, we will be required to withhold tax from the gross amount of the dividend at a rate of 30%, unless such Non-U.S. Holder is eligible for a reduced rate of withholding tax under an applicable income tax treaty and provides proper certification of its eligibility for such reduced rate (usually on an IRS Form W-8BEN or W-8BEN-E). Any distribution not constituting a dividend will be treated first as reducing (but not below zero) the Non-U.S. Holder’s adjusted tax basis in its shares of our Series A common stock and, to the extent such distribution exceeds the Non-U.S. Holder’s adjusted tax basis, as gain realized from the sale or other disposition of the Series A common stock, which will be treated as described under “U.S. Federal Income Tax Considerations to Non-U.S. Holders — Gain on Sale, Taxable Exchange or Other Taxable Disposition of Series A Common Stock.”

Dividends we pay to a Non-U.S. Holder that are effectively connected with such Non-U.S. Holder’s conduct of a trade or business within the United States (and, if a tax treaty applies, are attributable to a U.S. permanent establishment or fixed base maintained by the Non-U.S. holder) generally will not be subject to United States withholding tax, provided such Non-U.S. Holder complies with certain certification and disclosure requirements (usually by providing an IRS Form W-8ECI). Instead, such dividends generally will be subject to United States federal income tax, net of certain deductions, at the same graduated individual or corporate rates applicable to U.S. Holders (subject to an exemption or reduction in such tax as may be provided by an applicable income tax treaty). If the Non-U.S. Holder is a corporation, dividends that are effectively connected income may also be subject to a “branch profits tax” at a rate of 30% (or such lower rate as may be specified by an applicable income tax treaty).

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. WE ONCE AGAIN URGE YOU TO CONSULT WITH YOUR OWN TAX ADVISER TO DETERMINE THE PARTICULAR TAX CONSEQUENCES TO YOU (INCLUDING THE APPLICATION AND EFFECT OF ANY U.S. FEDERAL, STATE, LOCAL OR FOREIGN OR OTHER TAX LAWS) OF THE RECEIPT OF CASH IN EXCHANGE FOR SHARES IN CONNECTION WITH THE CHARTER AMENDMENT PROPOSAL.

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THE SPECIAL MEETING

Overview

Date, Time and Place. The Special Meeting of the Company’s stockholders will be held at 3:00 p.m. Eastern Time on December 15, 2023 as a virtual meeting. You will be able to attend, vote your shares and submit questions during the Special Meeting via a live webcast available at https://www.cstproxy.com/atlanticcoastalacquisitionii/sm2023. 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. The meeting will be held virtually over the internet by means of a live audio webcast. Only certain stockholders who own shares of our common stock as of the close of business on the record date will be entitled to attend the virtual meeting.

To register for the virtual meeting, please follow these instructions as applicable to the nature of your ownership of our common stock.

If your shares are registered in your name with our transfer agent and you wish to attend the online-only virtual meeting, go to https://www.cstproxy.com/atlanticcoastalacquisitionii/sm2023, enter the control number you received on your proxy card and click on the “Click here” to preregister for the online meeting link at the top of the page. Just prior to the start of the meeting you will need to log back into the meeting site using your control number. Pre-registration is recommended but is not required in order to attend.

Beneficial stockholders who wish to attend the online-only virtual meeting must obtain a legal proxy by contacting their account representative at the bank, broker, or other nominee that holds their shares and e-mail a copy (a legible photograph is sufficient) of their legal proxy to proxy@continentalstock.com. Beneficial stockholders who e-mail a valid legal proxy will be issued a meeting control number that will allow them to register to attend and participate in the online-only meeting. After contacting our transfer agent a beneficial holder will receive an e-mail prior to the meeting with a link and instructions for entering the virtual meeting. Beneficial stockholders should contact our transfer agent no later than 72 hours prior to the meeting date.

Stockholders will also have the option to listen to the Special Meeting by telephone by calling:

The passcode for telephone access: 5049363#. You will not be able to vote or submit questions unless you register for and log in to the Special Meeting webcast as described herein.

Voting Power; record date. You will be entitled to vote or direct votes to be cast at the Special Meeting, if you owned certain of the Company’s Series A common stock at the close of business on November 8, 2023, the record date for the Special Meeting. You will have one vote per proposal for each share of the Company’s common stock you owned at that time. The Company’s warrants do not carry voting rights.

Votes Required. Approval of the Charter Amendment Proposal will require the affirmative vote of holders of at least 65% of the Company’s common stock entitled to vote on the matter outstanding on the record date. If you do not vote or if you abstain from voting on a proposal, your action will have the same effect as an “AGAINST” vote. Broker non-votes will have the same effect as “AGAINST” votes.

At the close of business on the record date of the Special Meeting, there were 10,935,691 shares of Series A common stock and 1 share of Series B common stock outstanding. Of such shares of common stock, 7,499,999 have agreed not to vote until after the closing of a business combination (which amount represents converted Founder Shares), leaving 3,435,692 shares of Series A common stock and 1 share of Series B common stock eligible to vote at the Special Meeting.

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If you do not want the Charter Amendment Proposal approved, you must abstain, not vote, or vote “AGAINST” the Charter Amendment. You will be entitled to redeem your public shares for cash in connection with this vote whether or not you vote on the Charter Amendment Proposal so long as you elect to redeem your public shares for a pro rata portion of the funds available in the Trust Account in connection with the Charter Amendment Proposal. The Company anticipates that a public stockholder who tenders shares for redemption in connection with the vote to approve the Charter Amendment Proposal would receive payment of the redemption price for such shares soon after the completion of the Charter Amendment Proposal.

Proxies; Board Solicitation; Proxy Solicitor. Your proxy is being solicited by the Board on the proposals being presented to stockholders at the Special Meeting. The Company has engaged Morrow Sodali LLC to assist in the solicitation of proxies for the Special Meeting. No recommendation is being made as to whether you should elect to redeem your public shares. Proxies may be solicited in person or by telephone. If you grant a proxy, you may still revoke your proxy and vote your shares online at the Special Meeting if you are a holder of record of the Company’s common stock. You may contact the Proxy Solicitor at (800) 662-5200 (toll free) or by email at ACAB.info@investor.morrowsodali.com.

Required Vote

The affirmative vote by holders of at least 65% of the Company’s outstanding shares of common stock entitled to vote on the matter is required to approve the Charter Amendment Proposal. If the Charter Amendment Proposal is not approved, the Charter Amendment will not be implemented and, if a business combination has not been consummated, the Company will be required by its charter to (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, redeem 100% of the public shares, at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account, including interest earned and not previously released to the Company to pay its taxes, if any (less taxes payable and up to $100,000 of such net interest to pay dissolution expenses), divided by the number of then issued and outstanding public shares, which redemption will completely extinguish the rights of the Public Stockholders (as defined in the charter) as 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 Company’s remaining stockholders and the Company’s board of directors, dissolve and liquidate, subject (in the case of (ii) and (iii) above) to the Company’s obligations under the DGCL to provide for claims of creditors and other requirements of applicable law. Stockholder approval of the Charter Amendment is required for the implementation of our Board’s plan to extend the date by which we must consummate our initial business combination. Therefore, our Board will abandon and not implement such amendment unless our stockholders approve the Charter Amendment Proposal. Notwithstanding stockholder approval of the Charter Amendment Proposal, our Board will retain the right to abandon and not implement the Charter Amendment at any time without any further action by our stockholders.

Interests of our Sponsor, Directors and Officers

When you consider the recommendation of our Board, you should keep in mind that our Sponsor, executive officers, and members of our Board and special advisors have interests that may be different from, or in addition to, your interests as a stockholder. These interests include, among other things:

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Additionally, if the Charter Amendment Proposal is approved and we consummate an initial business combination, our Sponsor, officers and directors may have additional interests as will be described in the proxy statement for a business combination.

The Board’s Reasons for the Charter Amendment Proposal and Its Recommendation

As discussed below, after careful consideration of all relevant factors, our Board has determined that the Charter Amendment is in the best interests of the Company and its stockholders. Our Board has approved and declared advisable adoption of the Charter Amendment Proposal and recommends that you vote “FOR” such proposal.

Our charter provides that the Company has until December 19, 2023 to complete the purposes of the Company including, but not limited to, effecting a business combination under its terms. We entered into a term sheet with Abpro, a biotechnology company, on September 18, 2023, which sets forth the terms and conditions of a potential business combination with Abpro. As of the date of this proxy statement, we are actively negotiating a definitive agreement with Abpro. The term sheet provides for an exclusivity period currently expected to expire sixty days from September 18, 2023. There is no fee or penalty for either party in the event the term sheet is terminated or the contemplated business combination is not consummated. While we are using our best efforts to complete a business combination as soon as practicable, the Board believes that there will not be sufficient time before the Original Termination Date to complete a business combination with Abpro or any other party. Accordingly, the Board believes that in order to be able to consummate a business combination, we will need to obtain an Extension. Without an Extension, the Board believes that there is significant risk that we might not, despite our best efforts, be able to complete a business combination on or before December 19, 2023. If that were to occur, we would be precluded from completing a business combination and would be forced to liquidate even if our stockholders are otherwise in favor of consummating a business combination.

Our charter states that if the Company’s stockholders approve an amendment to the Company’s charter that would affect the substance or timing of the Company’s obligation to redeem 100% of the Company’s public shares if it does not complete a business combination before December 19, 2023, the Company will provide its public stockholders with the opportunity to redeem all or a portion of their public shares upon such approval at a per share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account, including interest (which interest shall be net of taxes payable), divided by the number of then outstanding public shares. We believe that this charter provision was included to protect the Company stockholders from having to sustain their investments for an unreasonably long period if the Company failed to find a suitable business combination in the timeframe contemplated by the charter.

In addition, the Company’s charter provides that the affirmative vote of the holders of at least 65% of all outstanding shares of common stock entitled to vote on the matter is required to extend our corporate existence,

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except in connection with, and effective upon the consummation of, a business combination. We believe that, given the Company’s expenditure of time, effort and money searching for potential business combination opportunities, circumstances warrant providing public stockholders an opportunity to consider a business combination. Because we continue to believe that a business combination would be in the best interests of our stockholders, the Board has determined to seek stockholder approval to extend the date by which we have to complete a business combination beyond December 19, 2023 to the Extended Date (or Additional Charter Extension Date, if applicable), in the event we cannot consummate a business combination by December 19, 2023.

The Company is not asking you to vote a business combination at this time. If the Extension to the Extended Date is implemented and you do not elect to redeem your public shares, you will retain the right to vote on a business combination in the future and the right to redeem your public shares at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account, including interest (which interest shall be net of taxes payable), divided by the number of then outstanding public shares, in the event a business combination is approved and completed or the Company has not consummated another business combination by the applicable Termination Date. After careful consideration of all relevant factors, the Board determined that the Charter Amendment is in the best interests of the Company and its stockholders.

Recommendation of the Board

Our Board unanimously recommends that our stockholders vote “FOR” the approval of the Charter Amendment Proposal.

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THE ADJOURNMENT PROPOSAL

Overview

The Adjournment Proposal, if adopted, will allow our Board to adjourn the Special Meeting to a later date or dates to permit further solicitation of proxies. The Adjournment Proposal will only be presented to our stockholders in the event that there are insufficient votes for, or otherwise in connection with, the approval of the Charter Amendment Proposal. In no event will our Board adjourn the Special Meeting beyond December 19, 2023.

Consequences if the Adjournment Proposal is Not Approved

If the Adjournment Proposal is not approved by our stockholders, our Board may not be able to adjourn the Special Meeting to a later date in the event that there are insufficient votes for, or otherwise in connection with, the approval of the Charter Amendment Proposal.

Vote Required for Approval

The approval of the Adjournment Proposal requires the affirmative vote of the majority of the votes cast by stockholders represented in person or by proxy at the Special Meeting. Accordingly, if a valid quorum is otherwise established, a stockholder’s failure to vote by proxy or online at the Special Meeting will have no effect on the outcome of any vote on the Adjournment Proposal. Abstentions will be counted in connection with the determination of whether a valid quorum is established but will have no effect on the outcome of the Adjournment Proposal.

Recommendation of the Board

Our Board unanimously recommends that our 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 by:

The following table sets forth information regarding the beneficial ownership of our Series A common stock, our Series B common stock, and our Series A common stock and Series B common stock voting together as a single group. The percentage ownership of our common stock is based on 10,935,692 shares of our common stock outstanding as of the record date, consisting of 10,935,691 shares of our Series A common stock and 1 share of our Series B common stock issued and outstanding. Of such shares of common stock, 7,499,999 are not entitled to vote until after the closing of a business combination (which amount represents converted Founder Shares), leaving 3,435,692 shares of Series A common stock and 1 share of Series B common stock eligible to vote at the Special Meeting.

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. The following table does not reflect record or beneficial ownership of the warrants offered in our IPO or the private placement warrants as such warrants are not exercisable within 60 days of the record date.

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HOUSEHOLDING INFORMATION

Unless we have received contrary instructions, we may send a single copy of this Proxy Statement to any household at which two or more stockholders reside if we believe 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 our expenses. However, if stockholders prefer to receive multiple sets of our 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 our disclosure documents, the stockholders should follow these instructions:

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WHERE YOU CAN FIND MORE INFORMATION

We file reports, proxy statements and other information with the SEC as required by the Exchange Act. You can read the Company’s SEC filings, including this Proxy Statement, 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 proposals to be presented at the Special Meeting, you should contact the Company’s proxy solicitation agent at the following address, telephone number and email:

Morrow Sodali LLC

333 Ludlow Street, 5th Floor, South Tower

Stamford, CT 06902

Tel: (800) 662-5200 (toll-free) or

(203) 658-9400 (banks and brokers can call collect)

Email: ACAB.info@investor.morrowsodali.com

You may also obtain these documents by requesting them via e-mail from the Company at IR@atlanticcoastal.io.

If you are a stockholder of the Company and would like to request documents, please do so by December 8, 2023, in order 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

AMENDMENT NO. 2 TO THE AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF ATLANTIC COASTAL ACQUISITION CORP. II

Pursuant to Section 242 of the

Delaware General Corporation Law

ATLANTIC COASTAL ACQUISITION CORP. II (the “Corporation”), a corporation organized and existing under the laws of the State of Delaware, does hereby certify 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, initially filed with the U.S. Securities and Exchange Commission (the “SEC”) on December 2, 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 withdrawal of interest to pay taxes, 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) not previously properly redeemed in accordance with clause (iii) below if the Corporation is unable to complete its initial Business Combination by February 19, 2024 (the “Termination Date”) (or up to August 19, 2024, if applicable in accordance with this Section 9.1(b)) or such earlier date as determined by the Board and (iii) the redemption of shares in connection with a vote seeking to amend such provisions of this Certificate as described in Section 9.7 hereof. Holders of shares of Common Stock included as part of the units 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 the Sponsor or officers or directors of the Corporation, or affiliates of any of the foregoing) are referred to herein as “Public Stockholders.” In the event that the Corporation has not consummated an initial Business Combination by the Termination Date, the Board may, without another stockholder vote, elect to extend the period of time to consummate a Business Combination on a monthly basis for up to six times by an additional one month each time after February 19, 2024, by resolution of the Board if requested by Atlantic Coastal Acquisition Management II LLC (the “Sponsor”), and upon five days’ advance notice prior to the applicable Termination Date, until

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August 19, 2024, provided that the Sponsor (or one or more of its affiliates or permitted designees) (the “Payor”) will deposit into the Trust Account the lesser of $10,000 or $0.015 for each then-outstanding Offering Share for each such monthly extension for an aggregate deposit of up to the lesser of $60,000 or $0.09 for each then-outstanding Offering Share (if all six additional monthly extensions are exercised).

“In the event that the Corporation has not consummated an initial Business Combination by the Termination Date (or up to August 19, 2024, if applicable in accordance with Section 9.1(b) above) or such earlier date as determined by the Board, the Corporation shall (i) cease all operations except for the purpose of winding up, (ii) as promptly as reasonably possible but not more than ten (10) business days thereafter subject to lawfully available funds therefor, redeem 100% of the Offering 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 not previously released to the Corporation to pay its taxes (less up to $100,000 of interest to pay dissolution expenses), by (B) the total number of then outstanding Offering 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 the Corporation’s obligations under the DGCL to provide for claims of creditors and other requirements of applicable law.”

“Additional Redemption Rights. If, in accordance with Section 9.1(a) hereof, any amendment is made to this Certificate (a) to modify the substance or timing of the Corporation’s obligation to redeem 100% of the Offering Shares if the Corporation has not consummated an initial Business Combination by Termination Date (or up to August 19, 2024, if applicable in accordance with Section 9.1(b) above) or such earlier date as determined by the Board or (b) with respect to any other material provisions of this Certificate relating to stockholders’ rights or pre-initial Business Combination activity, the Public Stockholders shall be provided with the opportunity to redeem their Offering Shares upon the approval of any such amendment, at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account, including interest not previously released to the Corporation to pay its taxes, divided by the number of then outstanding Offering Shares; provided, however, that any such amendment will be voided, and this Article IX will remain unchanged, if any stockholders who wish to redeem are unable to redeem due to the Redemption Limitation.”

IN WITNESS WHEREOF, Atlantic Coastal Acquisition Corp. II has caused this Amendment No. 2 to the Amended and Restated Certificate to be duly executed in its name and on its behalf by an authorized officer as of this day of [        ], 2023.

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ATLANTIC COASTAL ACQUISITION CORP. II

6 St Johns Lane, Floor 5

New York, NY 10013

SPECIAL MEETING OF STOCKHOLDERS

December 15, 2023

YOUR VOTE IS IMPORTANT

THIS PROXY IS SOLICITED BY THE BOARD OF DIRECTORS

FOR THE SPECIAL MEETING OF STOCKHOLDERS TO BE HELD ON DECEMBER 15, 2023

The undersigned, revoking any previous proxies relating to these shares, hereby acknowledges receipt of the Notice and Proxy Statement, dated December 1, 2023, in connection with the special meeting to be held at 3:00 p.m. Eastern Time on December 15, 2023 as a virtual meeting (the “Special Meeting”) for the sole purpose of considering and voting upon the following proposals, and hereby appoints Shahraab Ahmad and Jason Chryssicas (with full power to act alone), the attorneys and proxies of the undersigned, with full power of substitution to each, to vote all shares of the common stock of the Company registered in the name provided, which the undersigned is entitled to vote at the Special Meeting and at any adjournments thereof, with all the powers the undersigned would have if personally present. Without limiting the general authorization hereby given, said proxies are, and each of them is, instructed to vote or act as follows on the proposals set forth in the accompanying Proxy Statement.

THIS PROXY, WHEN EXECUTED, WILL BE VOTED IN THE MANNER DIRECTED HEREIN. IF NO DIRECTION IS MADE, THIS PROXY WILL BE VOTED “FOR” THE CHARTER AMENDMENT PROPOSAL (PROPOSAL 1), AND “FOR” THE ADJOURNMENT PROPOSAL (PROPOSAL 2), IF PRESENTED.

THE BOARD OF DIRECTORS RECOMMENDS A VOTE “FOR” ALL PROPOSALS.

Important Notice Regarding the Availability of Proxy Materials for the Special Meeting of Stockholders to be held on December 15, 2023: This notice of meeting and the accompanying proxy statement are available at https://www.cstproxy.com/atlanticcoastalacquisitionii/sm2023.

Signature should agree with name printed hereon. If stock is held in the name of more than one person, EACH joint owner should sign. Executors, administrators, trustees, guardians, and attorneys should indicate the capacity in which they sign. Attorneys should submit powers of attorney.

PLEASE SIGN, DATE AND RETURN THE PROXY IN THE ENVELOPE ENCLOSED TO CONTINENTAL STOCK TRANSFER & TRUST COMPANY. THIS PROXY WILL BE VOTED IN THE MANNER DIRECTED HEREIN BY THE UNDERSIGNED STOCKHOLDER. IF NO DIRECTION IS MADE, THIS PROXY WILL BE VOTED “FOR” THE PROPOSAL SET FORTH IN PROPOSAL 1, AND “FOR” THE PROPOSAL SET FORTH IN PROPOSAL 2, IF SUCH PROPOSAL IS PRESENTED AT THE SPECIAL MEETING. THIS PROXY WILL REVOKE ALL PRIOR PROXIES SIGNED BY YOU.