OneIM Acquisition Corp.

As filed with the U.S. Securities and Exchange Commission on December 22, 2025,

and is not being filed under the Securities Act of 1933, as amended.

Registration No. 333-_________

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORMS-1

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

ONEIM ACQUISITION CORP.

(Exact name of registrant as specified in its charter)

11 th Floor, 390 Park Avenue

New York, New York 10022

(646) 222 9570

(Address, Including Zip Code, and Telephone Number, Including Area Code, of Registrant’s Principal Executive Offices)

Ioannis Pipilis

Chief Executive Officer

11 th Floor, 390 Park Avenue

New York, New York 10022

Telephone: (646) 222 9570

(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 13(a) of the Exchange 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 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.

SUBJECT TO COMPLETION, DATED DECEMBER 22, 2025

PRELIMINARY PROSPECTUS

$250,000,000 ONEIM ACQUISITION CORP. 25,000,000 Units

OneIM Acquisition Corp. 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, 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. We may pursue an acquisition opportunity in any business, industry, sector or geographical location.

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-sixth 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. Accordingly, unless you purchase six public units, you will not be able to receive or trade a whole warrant. 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 underwriters have a 45-day option from the date of this prospectus to purchase up to an additional 3,750,000 units to cover over-allotments, if any.

We will provide our public shareholders with the opportunity 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 were 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 thereon (net of amounts withdrawn to fund working capital requirements, subject to the limitations described herein, and/or to pay our taxes (which shall exclude the 1% U.S. federal excise tax if any is imposed on us), divided by the number of then issued outstanding public shares, subject to the limitations and on the conditions described herein. The proceeds placed in the trust account and the interest earned thereon will 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 on any redemptions or stock buybacks by our 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 will 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 of certain limitations on redemption rights.

Our sponsor, OneIM Sponsor LLC (which we refer to as our sponsor throughout this prospectus), has committed to purchase an aggregate of 200,000 private units (including if the underwriters’ over-allotment option is exercised in full) at the initial public offering price of our public units of $10.00 per unit for an aggregate purchase price of $2,000,000 (including if the underwriters’ over-allotment option is exercised in full) in a private placement that will close simultaneously with the closing of this offering. These units, which we refer to as the private placement units, are identical to the public units sold in this offering, subject to limited exceptions as described in this prospectus.

Our initial shareholders, which include our sponsor, currently own an aggregate of 7,187,500 Class B ordinary shares, up to 937,500 of which are subject to forfeiture depending on the extent to which the underwriters’ over-allotment option is exercised. If we increase or decrease the size of this offering, we will effect a share capitalization or a share surrender 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 our initial shareholders, on an as-converted basis, at 20.00% of our issued and outstanding ordinary shares (excluding the private placement units) upon consummation of this offering. We refer to these Class B ordinary shares as the founder shares throughout this prospectus. After taking into account the issuance of the private placement units our initial shareholders will own an aggregate of 6,450,000 ordinary shares or 20.51% of our issued and outstanding ordinary shares immediately following the completion of this offering assuming the over-allotment option is not exercised, or an aggregate of 7,387,500 ordinary shares or 20.44% of our issued and outstanding ordinary shares immediately following the completion of this offering, assuming the over-allotment option is exercised in full.

The Class B ordinary shares will automatically convert into Class A ordinary shares at the time of our initial business combination, or at any time prior thereto at the option of the holder thereof, on a one-for-one basis, subject to adjustment as provided 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. In the case that additional Class A ordinary shares, or equity-linked securities (as described herein), are issued or deemed issued in excess of the amounts issued in this offering and related to the closing of our initial business combination, the ratio at which the Class B ordinary shares will convert into Class A ordinary shares will be adjusted (unless the holders of a majority of the issued and outstanding Class B ordinary shares agree to waive such anti-dilution adjustment with respect to any such issuance or deemed issuance) so that the number of Class A ordinary shares issuable upon conversion of all Class B ordinary shares will equal, in the aggregate, approximately 20.00% of the sum of (i) the total number of all Class A ordinary shares outstanding upon the completion of this offering (including any Class A ordinary shares issued pursuant to the underwriters’ over-allotment option), plus (ii) all Class A ordinary shares and equity-linked securities issued or deemed issued, in connection with the closing of the initial business combination (excluding any shares or equity-linked securities issued, or to be issued, to any seller in the initial business combination and any units issued to our sponsor or any of its affiliates or to our officers or directors upon conversion of working capital loans) minus (iii) any redemptions of Class A ordinary shares by public shareholders in connection with an initial business combination; provided that such conversion of founder shares will never occur on a less than one-for-one basis. As a result, the Class A ordinary shares issuable in connection with the conversion of the founder shares may result in material dilution to our public shareholders due to the anti-dilution rights of our founder shares that may result in an issuance of Class A ordinary shares on a greater than one-to-one basis upon conversion.

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 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 adopt new constitutional documents 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. 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 significantly dilute the implied value of your public shares in the event we consummate an 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.”

The nominal price that our sponsor paid for the founder shares creates an incentive whereby our sponsor 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 24 months (or 27 months if we have executed a definitive agreement for an initial business combination within 24 months from the closing of this offering) from the closing of this offering (as may be extended by 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), or by such earlier liquidation date as our board of directors may approve, the founder shares and private warrants will expire worthless, except to the extent they receive liquidating distributions from assets outside the trust account, which could create an incentive for our sponsor 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 or thereafter, we will repay up to $300,000 in loans made to us by our sponsor to cover offering-related and organizational expenses, and we will begin paying an affiliate of our sponsor $10,000 per month (the “Administrative Services Fee”) for office space, utilities and secretarial and administrative support. Our sponsor may also, but is not obligated to, enter into certain arrangements with us to finance transaction costs in connection with an initial business combination, including up to $1,500,000 of loans convertible into private placement units at a price of $10.00 per share at the option of the lender.

If we agree to pay our sponsor, officers or directors, advisors, or our or their affiliates a finder’s fee, advisory fee, consulting fee or success fee in order to effectuate the completion of our initial business combination, such persons 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 as any such fee may not be paid unless we consummate such business combination. We may also engage our sponsor or an affiliate of our sponsor as an advisor or otherwise in connection with our initial business combination and certain other transactions and pay such person or entity a salary or fee in an amount that constitutes a market standard for comparable transactions. Any such salary or fee would be paid using available working capital funds (including proceeds from any promissory notes issued by us and funds released from the trust account upon completion of our initial business combination), but would not in any event be paid out of the Administrative Services Fee. As of the date of this prospectus, no arrangements are currently in place with respect to the payment of any finder’s fee, advisory fee, consulting fee or success fee in order to effectuate the completion of our initial business combination, or with respect to the payment of a salary or other fee to our sponsor or an affiliate of our sponsor as an advisor or otherwise in connection with our initial business combination or any other transaction. 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. 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 the one hand, and purchasers in this offering on the other. As a result, there may be actual or potential material conflicts of interest between our sponsor and its 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 will lose their entire investment in us if our business combination is not completed, 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 (or 27 months if we have executed a definitive agreement for an initial business combination within 24 months from the closing of this offering) from the closing of this offering (as may be extended by 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) 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 24-month period, we may 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. There are no limitations on the number of times we may seek shareholder approval for an extension or the length of time of any such extension. However, if we seek shareholder approval for an extension, 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, divided by the number of then issued and outstanding public shares, subject to applicable law. If we are unable to complete our initial business combination within 24 months (or 27 months if we have executed a definitive agreement for an initial business combination within 24 months from the closing of this offering) from the closing of this offering, or by such earlier liquidation date as our board of directors may approve, 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 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 as further described herein.

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 Global Market tier of The Nasdaq Stock Market LLC, or Nasdaq, under the symbol “OIMAU,” 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 Deutsche Bank Securities Inc., the representative of the underwriters, 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 “OIM” and “OIMAW”, 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 page 53 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.

(1) Comprised of (i) $0.01 per unit on all units sold other than any units sold pursuant to the underwriters’ over-allotment option ($250,000 in the aggregate) that shall be paid upon the closing of this offering (with no incremental upfront underwriting discounts and commissions if the underwriters’ over-allotment option is exercised) and (ii) $0.55 per unit on all public units sold (up to $13,750,000 in the aggregate or up to $15,812,500 in the aggregate if the underwriters’ over-allotment option is exercised in full for deferred underwriting commissions to be deposited into a trust account located in the United States and released to Deutsche Bank Securities Inc. for its own account only upon the completion of an initial business combination. See the section of this prospectus entitled “Underwriting.”

Of the proceeds we receive from this offering and the sale of the private placement units described in this prospectus, $250.0 million or $287.5 million if the underwriters’ over-allotment option is exercised in full ($10.00 per unit in either case) will be deposited into a U.S.-based trust account with Continental Stock Transfer & Trust Company acting as trustee, and $2.0 million will be available to pay fees and expenses in connection with the closing of this offering and for working capital following the closing of this offering. Except with respect to up to $500,000 per year (plus the rollover of unused amounts from prior years) of interest earned on the funds held in the trust account that may be released to us to fund working capital requirements (provided that, only $125,000, plus the rollover of unused amounts from prior years, of interest earned on the funds held in the trust account may be released to us during the three month period that will begin 24 months from the closing of this offering if we have executed a definitive agreement for an initial business combination within 24 months from the closing of this offering), plus additional amounts of interest earned on the funds held in the trust account that may be released to us to pay our tax obligations (which shall exclude the 1% U.S. federal excise tax if any is imposed on us and which shall not be subject to the $500,000 annual limitation (or $125,000 limitation) described above) (“permitted withdrawals”), and up to $100,000 of dissolution expenses, if any, the proceeds from this offering and the sale of the private placement units will not be released from the trust account until the earliest to occur of (a) the completion of our initial business combination, (b) the redemption of any public shares properly tendered in connection with a shareholder vote to amend our amended and restated memorandum and articles of association (i) to modify the substance or timing of our obligation to redeem 100% of our public shares if we do not complete our initial business combination within 24 months (or 27 months if we have executed a definitive agreement for an initial business combination within 24 months from the closing of this offering), or such earlier liquidation date as our board of directors may approve, from the closing of this offering or (ii) with respect to any other provisions relating to shareholders’ rights or pre-initial business combination activity and (c) the redemption of all of our public shares if we are unable to complete our business combination within 24 months (or 27 months if we have executed a definitive agreement for an initial business combination within 24 months from the closing of this offering), or such earlier liquidation date as our board of directors may approve, from the closing of this offering, subject to applicable law. The proceeds deposited in the trust account could become subject to the claims of our creditors, if any, which could have priority over the claims of our public shareholders.

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 the section titled “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 our sponsor and our management team and their respective affiliates on the one hand, and purchasers in this offering on the other. See the sections titled “Summary — Conflicts of Interest”, “Proposed Business — Selection of a Target Business and Structuring of our Initial Business Combination” and “Management — Conflicts of Interest” for more information.

The underwriters are offering the shares for sale on a firm commitment basis. The underwriters expect to deliver the shares to the purchasers on or about , 2025.

Deutsche Bank Securities

, 2025