American Dynamism Acquisition Co

As filed with the Securities and Exchange Commission on September 30, 2025

Registration No. 333-

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM****S-1

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

(Exact name of registrant as specified in its charter)

1050 Connecticut Ave NW, Suite 500Washington, D.C. 20036Tel: (248) 890-7200

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

Anthony EisenbergChief Executive Officer1050 Connecticut Ave. NW, Suite 500Washington, D.C. 20036Tel: (248) 890-7200

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:

Approximate date of commencement of proposed sale to the public: As soon as practicable after the effective date of this registration statement.

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, check the following box.☐

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.☐

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.☐

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.☐

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

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act.☐

The Registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933, as amended, or until the Registration Statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

The information in this preliminary prospectus is not complete and may be changed. We may not sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell these securities and it is not soliciting an offer to buy these securities in any jurisdiction where the offer or sale is not permitted.

$200,000,000

20,000,000 Units

American Dynamism Acquisition Company is a blank check company incorporated as a Cayman Islands exempted company and formed for the purpose of effecting a merger, amalgamation, share exchange, asset acquisition, share purchase, reorganization or similar business combination with one or more businesses, or entities, which we refer to throughout this prospectus as our initial business combination. We have not selected any business combination target and we have not, nor has anyone on our behalf, initiated any substantive discussions, directly or indirectly, with any business combination target. Our efforts to identify a prospective initial business combination target will not be limited to a particular industry, sector or geographic region. While we may pursue an initial business combination in any business or industry, we expect to focus on a target in industries that complement our management team’s background, and to capitalize on the ability of our management team to identify and acquire a business, focusing on American companies in the defense, logistics, transportation, technology and AI sectors.

This is an initial public offering of our securities. Each unit has an offering price of $10.00 and consists of one Class A ordinary share and one-third of one redeemable warrant. Each whole warrant entitles the holder thereof to purchase one Class A ordinary share at a price of $11.50 per share, subject to adjustment as described herein. Only whole warrants are exercisable. No fractional warrants will be issued upon separation of the units and only whole warrants will trade. The warrants will become exercisable 30 days after the completion of our initial business combination, and will expire five years after the completion of our initial business combination or earlier upon redemption or our liquidation, as described herein. The underwriter has a 45-day option from the date of this prospectus to purchase up to an additional 3,000,000 units to cover over-allotments, if any.

We will provide our public shareholders with theopportunity to redeem, regardless of whether they abstain, vote for, or vote against, our initial business combination, all or a portion of their Class A ordinary shares that are sold as part of the units in this offering, which we refer to collectively as our public shares, upon the completion of our initial business combination at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the trust account described below as of two business days prior to the consummation of our initial business combination, including interest earned on the funds held in the trust account, net of taxes payable, divided by the number of then outstanding public shares, subject to the limitations and on the conditions described herein. Except for income taxes, the proceeds placed in the trust account and the interest earned thereon shall not be used to pay for possible excise tax or any other fees or taxes that may be levied on the Company pursuant to any current, pending or future rules or laws, including without limitation any excise tax due under the Inflation Reduction Act of 2022 (“IRA”) on any redemptions or stock buybacks by the Company.See“Summary — The Offering — Redemption rights for public shareholders upon completion of our initial business combination” and “Summary — The Offering — Redemption of public shares and distribution and liquidation if no initial business combination”** for more information**.

Notwithstanding the foregoing redemption rights, if we seek shareholder approval of our initial business combination and we do not conduct redemptions in connection with our initial business combination pursuant to the tender offer rules, our amended and restated memorandum and articles of association provide that a public shareholder, together with any affiliate of such shareholder or any other person with whom such shareholder is acting in concert or as a “group” (as defined under Section 13 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), will be restricted from redeeming its shares with respect to more than an aggregate of 15% of the shares sold in this offering without our prior consent. However, we would not be restricting our shareholders’ ability to vote all of their shares (including all shares held by those shareholders that hold more than 15% of the shares sold in this offering) for or against our initial business combination.See“Summary — The Offering — Limitation on redemption rights of shareholders holding 15% or more of the shares sold in this offering if we hold shareholder vote”** for further discussion on certain limitations on redemption rights**.

Our sponsor, Petit Monts LLC, and Cantor Fitzgerald & Co., the representative of the underwriter, have committed to purchase an aggregate of 4,000,000 private placement warrants (whether or not the underwriter’s over-allotment option is exercised in full), each exercisable to purchase one Class A ordinary share at $11.50 per share, at a price of $1.50 per warrant, or $6,000,000 in the aggregate, in a private placement that will close simultaneously with the closing of this offering. Of those 4,000,000 private placement warrants, our sponsor has agreed to purchase 2,666,667 warrants and Cantor Fitzgerald & Co. has agreed to purchase 1,333,333 warrants. Each private placement warrant is exercisable to purchase one Class A ordinary share at $11.50 per share.

Our sponsor has purchased an aggregate of 5,750,000 Class B ordinary shares for an aggregate of $25,000, up to 750,000 of which will be surrendered to us for no consideration after the closing of this offering depending on the extent to which the underwriter’s over-allotment option is exercised, which will automatically convert into Class A ordinary shares concurrently with or immediately following the consummation of our initial business combination, or earlier at the option of the holders thereof on a one-for-one basis, subject to the adjustments described herein. Because our sponsor acquired the Class B ordinary shares at a nominal price, our public shareholders will incur an immediate and substantial dilution upon the closing of this offering, assuming no value is ascribed to the warrants included in the units. Further, the Class A ordinary shares issuable in connection with the conversion of the Class B ordinary shares may result in material dilution to our public shareholders due to the anti-dilution rights of our Class B ordinary shares that may result in an issuance of Class A ordinary shares on a greater than one-to-one basis upon conversion. Additionally, our public shareholders may experience dilution from the exercise of the 4,000,000 private placement warrants to be purchased by our sponsor and Cantor Fitzgerald & Co. simultaneously with the closing of this offering as well as conversion of any working capital loans into equity, if elected by the sponsor. If we increase or decrease the size of this offering, we will effect a share capitalization or a share repurchase or redemption or other appropriate mechanism, as applicable, with respect to our Class B ordinary shares immediately prior to the consummation of this offering in such amount as to maintain the ownership of founder shares by our initial shareholders, on an as-converted basis, at 20% of our issued and outstanding ordinary shares upon the consummation of this offering. Any conversion of Class B ordinary shares described herein will take effect as a compulsory redemption of Class B ordinary shares and an issuance of Class A ordinary shares as a matter of Cayman Islands law. Such dilution could materially increase to the extent that the anti-dilution provision of the founder shares results in the issuance of Class A ordinary shares on a greater than one-to-one basis upon conversion of the founder shares at the time of our initial business combination to maintain the number of founder shares at 20%. Prior to the closing of our initial business combination, only holders of our Class B ordinary shares (i) will have the right to vote to appoint and remove directors prior to or in connection with the completion of our initial business combination and (ii) will be entitled to vote on continuing our company in a jurisdiction outside the Cayman Islands (including any special resolution required to amend our constitutional documents or to adopt new constitutional documents, in each case, as a result of our approving a transfer by way of continuation in a jurisdiction outside the Cayman Islands). On any other matters submitted to a vote of our shareholders prior to or in connection with the completion of our initial business combination, holders of the Class B ordinary shares and holders of the Class A ordinary shares will vote together as a single class, except as required by law. Collectively, the Class B ordinary shares and the shares underlying the private placement warrants will represent 25.2% of all ordinary shares outstanding, assuming the conversion of all warrants and that the underwriter’s over-allotment option is not exercised. Upon consummation of this offering or thereafter, we will repay up to $250,000 in loans made to us by our sponsor to cover offering-related and organizational expenses, and in the event that following this offering we obtain working capital loans from our sponsor to finance transaction costs related to our initial business combination, up to $1,500,000 of such loans may be convertible into warrants of the post-business combination entity at a price of $1.50 per warrant at the option of our sponsor. Additionally, our sponsor (including its members), officers, directors or advisors may be paid a finder’s fee, advisory fee, consulting fee or success fee in order to effectuate the completion of our initial business combination. Additionally, following consummation of a business combination, members of our management team will be entitled to reimbursement for any out-of-pocket expenses related to identifying, investigating and completing an initial business combination. Each of our independent directors currently owns 25,000 founder shares, which were transferred from our Sponsor to the independent directors in September 2025 (or approximately 1% of the outstanding founder shares, assuming the overallotment option is not exercised). As a result, there may be actual or potential material conflicts of interest between members of our management team, our sponsor and its affiliates on one hand, and purchasers in this offering on the other. See“Summary — Sponsor Information”, “Summary — The Offering — Founder Shares”, “Summary — The Offering — Transfer Restrictions on Founder Shares”,and“Summary — The Offering — Founder Shares Conversion and Anti-Dilution Rights”** and**“Risk Factors — Risks Relating to our Securities — The nominal purchase price paid by our sponsor for the founder shares may result in significant dilution to the implied value of your public shares upon the consummation of our initial business combination, and our sponsor is likely to make a substantial profit on its investment in us in the event we consummate an initial business combination, even if the business combination causes the trading price of our ordinary shares to materially decline.”** for further discussion on our sponsor’s and our affiliates’ securities and compensation**.

As more fully discussed in “Management — Conflicts of Interest,” each of our officers and directors presently has, and any of them in the future may have additional, fiduciary, contractual or other obligations or duties to one or more other entities pursuant to which such officer or director is or will be required to present a business combination opportunity to such entities. The low price that our sponsor, executive officers and directors (directly or indirectly) paid for the founder shares creates an incentive whereby our officers and directors could potentially make a substantial profit even if we select an acquisition target that subsequently

declines in value and is unprofitable for public shareholders. If we are unable to complete our initial business combination within the completion window, and do not hold a shareholder vote to amend our amended and restated memorandum and articles of association to extend the amount of time we will have to consummate an initial business combination, or by such earlier liquidation date as our board of directors may approve, the founder shares and private placement warrants may expire worthless, except to the extent they receive liquidating distributions from assets outside the trust account, which could create an incentive for our sponsor, executive officers and directors to complete a transaction even if we select an acquisition target that subsequently declines in value and is unprofitable for public shareholders. Further, each of our officers and directors may have a conflict of interest with respect to evaluating a particular business combination if the retention or resignation of any such officers and directors was included by a target business as a condition to any agreement with respect to our initial business combination. Upon consummation of this offering, we will repay up to $250,000 in loans made to us by our sponsor to cover offering-related and organizational expenses. In the event that following this offering we obtain working capital loans from our sponsor to finance transaction costs related to our initial business combination, up to $1,500,000 of such loans may be convertible into warrants of the post-business combination entity at a price of $1.50 per warrant at the option of our sponsor. As a result, there may be actual or potential material conflicts of interest between members of our management team, our sponsor and their affiliates on the one hand, and purchasers in this offering on the other hand.See the sections titled“Summary — Sponsor Information”, “Summary — Conflicts of Interest”, “Risk Factors — Risks Relating to our Search for, and Consummation of or Inability to Consummate, a Business Combination — Since our sponsor, officers and directors, and any other holder of our founder shares, may lose their entire investment in us if our initial business combination is not completed (other than with respect to public shares they may acquire during or after this offering), a conflict of interest may arise in determining whether a particular business combination target is appropriate for our initial business combination.”and“Management — Conflicts of Interest” for more information.

We have until the date that is 24 months from the closing of this offering or until such earlier liquidation date as our board of directors may approve, to consummate our initial business combination. If we anticipate that we may be unable to consummate our initial business combination within such time period and we wish to further extend the date by which we must consummate our initial business combination, we will seek shareholder approval to amend our amended and restated memorandum and articles of association to extend the date by which we must consummate our initial business combination (an “extension”), and holders of public shares will be offered an opportunity to redeem their shares at a per share price, payable in cash, equal to the aggregate amount then on deposit in the trust account, including interest earned thereon (net of taxes payable), divided by the number of then issued and outstanding public shares, subject to applicable law. Such amendment to our amended and restated memorandum and articles of association may include limitations on the duration of the extension, the number of possible extensions, requirements for additional payments to the trust in connection with an extension, and other potential terms for consideration by our shareholders. If we are unable to complete our initial business combination within the time period described above (including any extensions), which we refer to throughout this prospectus as the completion window, we will 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 thereon (net of taxes payable and up to $100,000 of interest income to pay dissolution expenses), divided by the number of then issued and outstanding public shares, subject to applicable law and certain conditions as further described herein.

If we have not completed our initial business combination within the completion window, we will cease all operations except for the purpose of winding up, redeem the public shares, and, subject to the approval of our remaining shareholders and our board of directors, liquidate and dissolve, subject in each case to our obligations under Cayman Islands law to provide for claims of creditors and the requirements of other applicable law. There will be no redemption rights or liquidating distributions with respect to our rights, which will expire worthless if we fail to complete our initial business combination within the completion window.See “Summary — The Offering — Redemption of public shares and distribution and liquidation if no initial business combination.”

Currently, there is no public market for our units, Class A ordinary shares or warrants. We intend to apply to have our units listed on The Nasdaq Global Market, or Nasdaq, under the symbol “ADACU,” on or promptly after the date of this prospectus. We cannot guarantee that our securities will be approved for listing on Nasdaq. We expect the Class A ordinary shares and warrants comprising the units to begin separate trading on the 52 nd day following the date of this prospectus unless Cantor Fitzgerald & Co., the representative of the underwriter, informs us of its decision to allow earlier separate trading, subject to our satisfaction of certain conditions as described further herein. Once the securities comprising the units begin separate trading, we expect that the Class A ordinary shares and warrants will be listed on Nasdaq under the symbols “ADAC” and “ADACW”, respectively.

We are an “emerging growth company” and a “smaller reporting company” under applicable federal securities laws and will be subject to reduced public company reporting requirements. Investing in our securities involves a high degree of risk. See “Risk Factors” beginning on page43** for a discussion of information that should be considered in connection with an investment in our securities. Investors will not be entitled to protections normally afforded to investors in Rule 419 blank check offerings.**

Neither the U.S. Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

No offer or invitation, whether directly or indirectly, is being or may be made to the public in the Cayman Islands to subscribe for any of our securities.

Of the proceeds we receive from this offering and the sale of the private placement warrants described in this prospectus, $200 million, or $230 million if the underwriter’s overallotment option is exercised in full ($10.00 per unit in either case), will be placed into a U.S.-based trust account with Continental Stock Transfer & Trust Company acting as trustee.

Because our sponsor acquired the founder shares at a nominal price, our public shareholders will incur an immediate and substantial dilution upon the closing of this offering, assuming no value is ascribed to the warrants included in the units. Further, the Class A ordinary shares issuable in connection with the conversion of the founder shares, and private any placement warrants of the post-business combination entity issuable in connection with the conversion of up to $1,500,000 of working capital loans into private placement warrants at a price of $1.50 per warrant, may also result in material dilution to our public shareholder. Such dilution could materially increase to the extent that the anti-dilution provisions of the founder shares result in the issuance of Class A ordinary shares on a greater than one-to-one basis upon conversion of the founder shares at the time of our initial business combination to maintain the number of founder shares at 20%.**See “**Summary — The Offering — Founder Shares Conversion and Anti-Dilution Rights.” In addition, our board of directors is not currently contemplating and does not anticipate approving any share capitalizations in the foreseeable future, except if we increase the size of this offering, in which case we will effect a share capitalization or other appropriate mechanism immediately prior to the consummation of this offering in an amount necessary to maintain the number of founder shares at 20% of our issued and outstanding ordinary shares upon the consummation of this offering, which may result in further material dilution to our public shareholders.See the sections titled “Dividend Policy,” “Risk Factors — Risks Relating to our Securities — The nominal purchase price paid by our sponsor for the founder shares may result in significant dilution to the implied value of your public shares upon the consummation of our initial business combination, and our sponsor is likely to make a substantial profit on its investment in us in the event we consummate an initial business combination, even if the business combination causes the trading price of our ordinary shares to materially decline.” and “Risk Factors — Risks Relating to our Search for, and Consummation of or Inability to Consummate, a Business Combination — We may issue additional Class A ordinary shares or preference shares to complete our initial business combination or under an employee incentive plan after completion of our initial business combination. We may also issue Class A ordinary shares upon the conversion of the founder shares at a ratio greater than one-to-one at the time of our initial business combination as a result of the anti-dilution provisions contained therein. Any such issuances would dilute the interest of our shareholders and likely present other risks.”

The following table illustrates the difference between the public offering price per unit and our net tangible book value per share (NTBV), as adjusted to give effect to this offering and assuming the redemption of our public shares at varying levels and the exercise in full and no exercise of the over-allotment option.See section entitled “Dilution” for more information.

Our sponsor and members of our management team will directly or indirectly own our securities following this offering, and accordingly, they may have a conflict of interest in determining whether a particular target business is an appropriate business with which to effectuate our initial business combination. Additionally, each of our officers and directors presently has, and any of them in the future may have additional, fiduciary, contractual or other obligations or duties to one or more other entities pursuant to which such officer or director is or will be required to present a business combination opportunity to such entities. As a result, there may be actual or potential material conflicts of interest between members of our management team, our sponsor and their affiliates on one hand, and purchasers in this offering on the other. See the sections titled“Summary — Conflicts of Interest”, “Proposed Business — Sourcing of Potential Business Combination Targets” and “Management — Conflicts of Interest” for more information**.**

The underwriter is offering the units for sale on a firm commitment basis. The underwriter expects to deliver the units to the purchasers on or about [●], 2025.

Sole Book-Running Manager

Cantor

, 2025