Bio immediately prior to the Closing, provided that if the Oak Hill Bio SAFEs remain outstanding for a period of 18 months from the date of execution, the Oak Hill Bio SAFEs will convert into Oak Hill Bio’s Series A convertible preferred shares (the “OHB Series A Shares”). The sum of the principal amount of the Oak Hill Bio SAFEs and all accrued and unpaid interest thereon as of the Closing Date is referred to as the “Oak Hill Bio SAFE Amount.” The Oak Hill Bio SAFE Amount is added to the Base Equity Value to determine the Adjusted Equity Value for purposes of calculating the Closing Consideration.

Concurrently with the execution of the Business Combination Agreement, on July 26, 2026, RACC entered into subscription agreements (the “Subscription Agreements”) with certain qualified institutional buyers, institutional accredited investors, and other accredited investors (collectively, the “PIPE Investors”). Pursuant to the Subscription Agreements, the PIPE Investors have agreed to subscribe for and purchase, and RACC has agreed to issue and sell to the PIPE Investors, substantially concurrently with the Closing, (a) shares of New OHB Common Stock at $10.00 per share and/or (b) pre-funded warrants to purchase shares of New OHB Common Stock (the “New OHB Pre-Funded Warrants”), each to purchase one share of New OHB Common Stock, with a per share exercise price equal to $0.0001, at a purchase price per New OHB Pre-Funded Warrant equal to $10.00 less the exercise price (collectively, the “PIPE Financing”). The aggregate gross proceeds to be received by RACC in connection with the PIPE Financing will be $55,000,000. The obligations of each party to consummate the PIPE Financing are conditioned upon, among other things, (i) the New OHB Common Stock (including the New OHB Common Stock issuable to the PIPE Investors pursuant to the Subscription Agreements) having been approved for listing on Nasdaq; (ii) all conditions precedent to the Closing shall have been satisfied (or otherwise waived in accordance with the terms thereof); and (iii) the absence of specified adverse judgments, orders, laws, rules or regulations enjoining or otherwise prohibiting the consummation of the Transactions. See “Business Combination Proposal—Related Agreements—PIPE Financing.”

Concurrently with the execution of the Business Combination Agreement on July 26, 2026, RACC entered into the backstop agreement (the “Backstop Agreement”) with RA Capital Healthcare Fund, L.P., an affiliate of the Sponsor (the “RA Backstop Purchaser”), pursuant to which the RA Backstop Purchaser has committed to subscribe for up to 7,500,000 shares of New OHB Common Stock at a purchase price of $10.00 per share (the “Backstop Limit”), to the extent necessary to backstop public shareholder redemptions, on the terms and subject to the conditions set forth in the Backstop Agreement. Immediately prior to the Domestication, RACC will effect the redemption of the public shares initially issued in RACC’s initial public offering that are validly submitted for redemption and not withdrawn. The Backstop Limit will be reduced by the number of shares of New OHB Common Stock not subject to public shareholder redemptions. The aggregate amount the RA Backstop Purchaser will be required to fund shall not exceed $75,000,000. See “Business Combination Proposal—Related Agreements—Backstop Agreement.”

The public shareholders currently own approximately 82.4% of the issued and outstanding RACC Shares prior to the Transactions. Accordingly, public shareholders, as a group, will experience immediate dilution as a consequence of the Transactions. For more information on the percentage of the issued and outstanding shares of New OHB Common Stock immediately following the Closing that are expected to be held by securityholders, see “Dilution.”

Pursuant to the Business Combination Agreement, public shareholders who do not redeem their public shares will receive one share of New OHB Common Stock for each RACC Class A Share held by them immediately prior to the Domestication. While RACC cannot be certain of the price such public shareholders paid for their public shares, assuming they purchased their public shares for $10.00 per share, which was the price of the RACC Class A Shares sold in RACC’s initial public offering, the effective purchase price paid per share of New OHB Common Stock issued to each public shareholder at Closing would be $10.00. In connection with RACC’s initial public offering, the Sponsor paid an aggregate of $25,000 for the 1,323,529 RACC Class B Shares, or approximately $0.02 per share. In connection with the Transactions, an aggregate of 1,245,269 RACC Class B Shares held by the Sponsor and an additional 78,260 RACC Class B Shares held by Michael F. MacLean and Timothy J. Miller (the “RACC independent directors”), will be converted on a one-for-one basis into RACC Class A Shares immediately prior to the Domestication, which will then automatically convert at the effective time of the Domestication into an equal number of shares of New OHB Common Stock, valued at $10.00 per

share, which is the assumed per share price used in the Transactions pursuant to the Business Combination Agreement. The Sponsor also purchased 275,000 RACC Class A Shares at a price of $10.00 per share in a private placement that occurred simultaneously with the closing of RACC’s initial public offering. Such private placement shares will automatically convert at the effective time of the Domestication into an equal number of shares of New OHB Common Stock valued at $10.00 per share, which is the assumed per share price used in the Transactions pursuant to the Business Combination Agreement. The Oak Hill Bio Shareholders (including the SAFE Holders and shares underlying Company Options (as defined in the Business Combination Agreement)) will receive an aggregate of 16,000,000 shares of New OHB Common Stock in the Transactions upon the exchange of Oak Hill Bio Shares, based on the Base Equity Value of $160,000,000 divided by $10.00 per share. The PIPE Investors will purchase 5,500,000 shares of New OHB Common Stock and/or New OHB Pre-Funded Warrants, which is equal to $55,000,000 divided by $10.00. As a result of the low price the Sponsor paid for the RACC Class B Shares, the Sponsor may realize a positive rate of return on its investment even if the market price per share of New OHB Common Stock is below $10.00 per share after Closing, in which case the public shareholders may experience a negative rate of return on their investment. See “Questions and Answers for Shareholders of RACC—What is the effective purchase price attributed to the New OHB Common Stock to be received by the public shareholders, the Sponsor, RACC’s independent directors (Messrs. MacLean and Miller), and the Oak Hill Bio Shareholders at Closing?”

In connection with the Closing, the Sponsor, the RACC independent directors, and certain existing Oak Hill Bio Shareholders will each enter into a lock-up agreement (the “Lock-Up Agreement”) with RACC. Pursuant to the Lock-Up Agreement, the Sponsor, the RACC independent directors, and certain existing Oak Hill Bio Shareholders will agree not to transfer (except for certain permitted transfers) any shares of New OHB Common Stock held by such holder immediately after the Closing (excluding shares issued pursuant to the Subscription Agreements, the Oak Hill Bio SAFEs, and the Backstop Agreement) until six months after the Closing Date.

Additionally, at the Closing, RACC, the Sponsor, the SAFE Holders, the RA Backstop Purchaser, the RACC independent directors, and all former Oak Hill Bio Shareholders will enter into an investor rights agreement (the “Investor Rights Agreement”). Pursuant to the Investor Rights Agreement, among other things, RACC will agree that, within 30 calendar days following the Closing Date, New Oak Hill Bio will file with the SEC (at New Oak Hill Bio’s sole cost and expense) a registration statement registering the resale of certain shares of New OHB Common Stock held by or issuable to the parties thereto (the “Resale Registration Statement”), and New Oak Hill Bio will use its commercially reasonable efforts to have the Resale Registration Statement declared effective as soon as reasonably practicable after the filing thereof. Such holders will be entitled to customary piggyback registration rights and demand registration rights, including underwritten demands. The Investor Rights Agreement will amend and restate the registration and shareholder rights agreement that was entered into by RACC, the Sponsor and the RACC independent directors in connection with RACC’s initial public offering.

Compensation to be Received by the Sponsor, the SAFE Holders, the RA Backstop Purchaser and RACC’s Officers and Directors in Connection with the Transactions and the Oak Hill Bio SAFEs: The Sponsor will receive (i) 1,245,269 shares of New OHB Common Stock upon the exchange of 1,245,269 RACC Class B Shares, which were initially purchased in connection with RACC’s initial public offering for approximately $0.02 per share and (ii) 275,000 shares of New OHB Common Stock upon the exchange of 275,000 RACC Class A Shares, which were initially purchased in a private placement that closed concurrently with RACC’s initial public offering for $10.00 per share. The RACC independent directors will each receive 39,130 shares of New OHB Common Stock upon the exchange of 39,130 RACC Class B Shares held by them. Concurrently with the execution of the Business Combination Agreement, the SAFE Holders entered into the Oak Hill Bio SAFEs, which will convert into ordinary shares of Oak Hill Bio immediately prior to the Closing, which will then be exchanged for shares of New OHB Common Stock in the Share Acquisition, provided that if the Oak Hill Bio SAFEs remain outstanding for a period of 18 months from the date of execution, the Oak Hill Bio SAFEs will convert into Series A convertible preferred shares of Oak Hill Bio (the “OHB Series A Shares”). The securities to be issued to the Sponsor, the SAFE Holders and RACC’s officers and directors may result in a material dilution of the equity interests of non-redeeming public shareholders. See “Dilution,” and “Information About RACC—Executive Compensation and Director Compensation.”

The Sponsor and RACC’s officers and directors will also be reimbursed for loans, advances, and out-of-pocket expenses incurred by them related to identifying, negotiating, investigating and completing the Transactions. No such loans, advances, or out-of-pocket expenses are outstanding as of the date of this proxy statement/prospectus. The Sponsor and RACC’s officers and directors will be entitled to continued indemnification and the continuation of directors’ and officers’ liability insurance after the Transactions.

RACC’s independent directors are not members of the Sponsor. None of the funds in the trust account will be used to compensate RACC’s officers or directors. No finder’s and consulting fees have been paid or will be paid to the Sponsor, officers and directors, or any of their respective affiliates, for services rendered prior to or in connection with the completion of the Transactions. However, these individuals will be reimbursed for any out-of-pocket expenses incurred in connection with activities performed on our behalf such as identifying potential target businesses and performing due diligence on suitable business combinations, as discussed above. The reimbursement of expenses and advances to the Sponsor, and RACC’s officers and directors may result in a material dilution of the equity interests of non-redeeming public shareholders. See “Dilution,” and “Information About RACC—Executive Compensation and Director Compensation.”

Potential conflicts of interest in connection with the Transactions: There may be actual or potential material conflicts of interest between or among (i) the Sponsor, the SAFE Holders, the RA Backstop Purchaser, RACC officers and directors, Oak Hill Bio officers and directors and (ii) unaffiliated security holders of RACC. Such conflicts of interest may include a material conflict of interest arising in determining whether to proceed with the Transactions, the shares of New OHB Common Stock to be issued to the Sponsor and RACC’s officers and directors in connection with the Transactions, and the reimbursement of loans and advances.

In order to finance transaction costs in connection with the Transactions, the Sponsor or an affiliate of the Sponsor, or certain of RACC’s officers and directors may, but are not obligated to, loan RACC funds as may be required (“Working Capital Loans”). If RACC completes the Transactions, RACC may repay the Working Capital Loans out of the proceeds of the trust account released to RACC. Otherwise, the Working Capital Loans may be repaid only out of funds held outside the trust account. In the event that the Transactions do not close, RACC may use a portion of the proceeds held outside the trust account or funds from permitted withdrawals to repay the Working Capital Loans, but no proceeds held in the trust account would be used to repay the Working Capital Loans. Except for the foregoing, the terms of such Working Capital Loans, if any, have not been determined and no written agreements exist with respect to such loans. The Working Capital Loans would either be repaid upon consummation of a business combination, without interest, or, at the lender’s discretion, up to $3,000,000 of such Working Capital Loans may be convertible into shares of New OHB Common Stock at a price of $10.00 per share. To date, RACC has no outstanding borrowings under the Working Capital Loans.

The approval of each of the Domestication Proposal and the Governing Documents Proposal requires a special resolution of the holders of RACC Class B Shares, being the affirmative vote of at least a two-thirds (2/3) majority of the votes cast by the holders of the issued and outstanding RACC Class B Shares present in person or represented by proxy at the extraordinary general meeting and entitled to vote on such matter. The approval of each of the Business Combination Proposal, the Advisory Governing Documents Proposals, the Nasdaq Proposal, the Equity Incentive Plan Proposal, the Employee Stock Purchase Plan Proposal and the Adjournment Proposal requires an ordinary resolution under Cayman Islands law, being the affirmative vote of at least a majority of the votes cast by the holders of the issued and outstanding RACC Shares present in person or represented by proxy at the extraordinary general meeting and entitled to vote on such matter. The Transactions do not require approval of a majority of unaffiliated security holders because such a vote is not required under Cayman Islands law. RACC did not retain an unaffiliated representative to act solely on behalf of unaffiliated security holders for purposes of negotiating the terms of the Transactions or to prepare a report concerning the approval of the Transactions.

Please note that as further described in the accompanying proxy statement/prospectus, the Sponsor and each independent director has agreed to (a) vote any of their RACC Shares in favor of the Transactions and (b) waive their redemption rights with respect to any RACC Shares they own in connection with the consummation of the Transactions. As of the date of the accompanying proxy statement/prospectus, the initial shareholders

collectively own 1,598,529 RACC Shares, or approximately 17.6% of the issued and outstanding ordinary shares as follows: (i) the Sponsor owns 1,245,269 RACC Class B Shares and 275,000 private placement shares, which are RACC Class A Shares; and (ii) the RACC independent directors each own 39,130 RACC Class B Shares, for an aggregate of 78,260 RACC Class B Shares. Concurrently with the execution of the Business Combination Agreement, RACC, the Sponsor, the RACC independent directors and Oak Hill Bio entered into the Sponsor Letter Agreement (the “Sponsor Letter Agreement”), pursuant to which the Sponsor and each independent director has agreed to, among other things, (i) vote in favor of the Business Combination Agreement and the Transactions, (ii) waive any adjustment to the conversion ratio set forth in the governing documents of RACC or any other anti-dilution or similar protection with respect to the RACC Class B Shares (whether resulting from the transactions contemplated by the Subscription Agreements or otherwise), (iii) be bound by certain other covenants and agreements related to the Transactions, (iv) be bound by certain transfer restrictions with respect to his or its RACC Shares prior to the Closing, and (v) be subject to the restrictions contemplated by the Lock-Up Agreements, in each case, on the terms and subject to the conditions set forth in the Sponsor Letter Agreement. No consideration has been or will be paid to RACC, Oak Hill Bio, the Sponsor or any independent director in connection with the entry into the Sponsor Letter Agreement. Pursuant to our amended and restated memorandum and articles of association, a quorum will be present at the extraordinary general meeting if one or more shareholders who together hold not less than one-third of the issued and outstanding RACC Shares entitled to vote at the extraordinary general meeting are represented in person or by proxy at the extraordinary general meeting. Accordingly, we will need at least 1,434,314 RACC Shares, in addition to the RACC Shares held by the initial shareholders, to constitute a quorum. Approval of each of the Business Combination Proposal, the Advisory Governing Documents Proposals, the Nasdaq Proposal, the Equity Incentive Plan Proposal, the Employee Stock Purchase Plan Proposal and the Adjournment Proposal requires an ordinary resolution under Cayman Islands law, being the affirmative vote of at least a majority of the votes cast by the holders of the issued and outstanding RACC Shares present in person or represented by proxy at the extraordinary general meeting and entitled to vote on such matter. Accordingly, we will need 4,549,265 RACC Shares, or 2,950,736 public shares in addition to the RACC Shares held by the initial shareholders, to vote in favor of each of the Business Combination Proposal, the Advisory Governing Documents Proposals, the Nasdaq Proposal, the Equity Incentive Plan Proposal, the Employee Stock Purchase Plan Proposal and the Adjournment Proposal to approve it if all RACC Shares are present and cast votes. If only the minimum quorum is present, no public shares will be required to vote in favor of each of the Business Combination Proposal, the Advisory Governing Documents Proposals, the Nasdaq Proposal, the Equity Incentive Plan Proposal, the Employee Stock Purchase Plan Proposal and the Adjournment Proposal to approve it.

This prospectus covers 9,098,529 shares of New OHB Common Stock only. The number of shares of New OHB Common Stock that this prospectus covers represents the shares issued or issuable to the existing shareholders of RACC in connection with the Transactions, assuming no public shares are redeemed in connection with the Transactions.

For the avoidance of doubt, shares of New OHB Common Stock to be issued in connection with the Transactions to (i) Oak Hill Bio Shareholders (including the SAFE Holders); (ii) the PIPE Investors; and (iii) the RA Backstop Purchaser, in connection with the Transactions, are not covered by this prospectus. Such shares of New OHB Common Stock will not be and have not been registered under the Securities Act in reliance on the exemption from registration provided in Section 4(a)(2) of the Securities Act, and therefore will be “restricted securities” within the meaning of the Securities Act until further registration under the Securities Act. Pursuant to the Investor Rights Agreement and the Subscription Agreements, New Oak Hill Bio has agreed to use its commercially reasonable efforts to file a resale registration statement under the Securities Act, not later than 30 days following the consummation of the Transactions to register certain registrable securities held by the parties thereto.

RACC Class A Shares are currently listed on the Nasdaq Capital Market (“Nasdaq”) under the symbol “RACC.” RACC will apply for listing, to be effective at the time of the Transactions, of the New OHB Common Stock on Nasdaq under the proposed symbol “OAKH.” It is a condition of the consummation of the Transactions and a condition to the obligations of the parties to the Subscription Agreements to consummate the PIPE Financing, that RACC receive confirmation from Nasdaq that the New OHB Common Stock has been

conditionally approved for listing on Nasdaq, but there can be no assurance that such listing condition will be met or that RACC will obtain such confirmation from Nasdaq. If such listing condition is not met or if such confirmation is not obtained, the Transactions and the PIPE Financing will not be consummated unless the Nasdaq condition set forth in the Business Combination Agreement and the Subscription Agreements is waived by the applicable parties. The Nasdaq listing condition may be waived by Oak Hill Bio and RACC, with respect to the Transactions, and by the PIPE Investors, with respect to the PIPE Financing, at any time prior to the Closing, including after the deadline for submitting redemption requests or the extraordinary general meeting. If Oak Hill Bio and RACC, on the one hand, and/or the PIPE Investors, on the other hand, waive such condition, RACC intends to file a Current Report on Form 8-K within four business days of such event, however you should know that given such timing you may not be notified before the deadline for submitting redemption requests or the extraordinary general meeting. It is important for you to consider that, at the time of the deadline for submitting redemption requests or the extraordinary general meeting, RACC may not have received from Nasdaq either confirmation of the listing of the New OHB Common Stock or confirmation that approval will be obtained prior to the consummation of the Transactions, and you will not be notified prior to the deadline for submitting redemption requests or the extraordinary general meeting if RACC has not yet received such approval or confirmation. As a result, you may be asked to vote to approve the Transactions and the other proposals included in this proxy statement/prospectus without knowing whether the New OHB Common Stock will be listed on Nasdaq or another securities exchange and, further, it is possible that such listing may never be achieved and the Transactions could still be consummated if such Nasdaq listing condition is waived.

RACC is, and New Oak Hill Bio will be, an “emerging growth company” as defined in the Jumpstart Our Business Startups Act of 2012 and has elected to comply with certain reduced public company reporting requirements. Investing in New OHB Common Stock involves a high degree of risk. See “Risk Factors” beginning on page 61 of the accompanying proxy statement/prospectus for a discussion of information that should be considered in connection with an investment in New OHB Common Stock.

The accompanying proxy statement/prospectus provides shareholders of RACC with detailed information about the Transactions and other matters to be considered at the extraordinary general meeting of RACC. We encourage you to read the entire accompanying proxy statement/prospectus, including the Annexes and other documents referred to therein, carefully and in their entirety. You should also carefully consider the risk factors described in “Risk Factors” beginning on page 61 of the accompanying proxy statement/prospectus.

NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES REGULATORY AGENCY HAS APPROVED OR DISAPPROVED THE TRANSACTIONS DESCRIBED IN THE ACCOMPANYING PROXY STATEMENT/PROSPECTUS, PASSED UPON THE MERITS OR FAIRNESS OF THE BUSINESS COMBINATION OR RELATED TRANSACTIONS OR PASSED UPON THE ADEQUACY OR ACCURACY OF THE DISCLOSURE IN THE ACCOMPANYING PROXY STATEMENT/PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY CONSTITUTES A CRIMINAL OFFENSE.

The accompanying proxy statement/prospectus is dated [●], 2026, and

is first being mailed to RACC’s shareholders on or about [●], 2026.

RESEARCH ALLIANCE CORPORATION III

600 Fifth Avenue, 23rd Floor

New York, New York 10020

Dear Research Alliance Corporation III Shareholders:

You are cordially invited to attend the extraordinary general meeting (the “extraordinary general meeting”) of Research Alliance Corporation III, a Cayman Islands exempted company (“RACC”), at 10:00 a.m., Eastern Time, on [●], 2026, at the offices of Cooley LLP located at 55 Hudson Yards, New York, New York 10001, and via a virtual meeting at [●], or at such other time, on such other date and at such other place to which the meeting may be adjourned.

The extraordinary general meeting will be conducted via live webcast, but the physical location of the extraordinary general meeting will remain at the location specified above for the purposes of our amended and restated memorandum and articles of association. If you wish to attend the extraordinary general meeting in person, you must reserve your attendance at least two business days in advance of the extraordinary general meeting by contacting RACC’s secretary at RACC@racap.com by 10:00 a.m., Eastern Time, on [●], 2026. You will be able to attend the extraordinary general meeting online, vote and submit your questions during the extraordinary general meeting by visiting [●].

At the extraordinary general meeting, RACC shareholders will, among others, be asked to consider and vote upon a proposal, which is referred to herein as the “Business Combination Proposal” to approve and adopt the Business Combination Agreement, dated as of July 26, 2026 (as it may be amended, supplemented or otherwise modified from time to time, the “Business Combination Agreement”), by and among RACC, OHB Pediatrics Ltd., a company incorporated under the laws of England and Wales (“Oak Hill Bio”), and the Oak Hill Bio Shareholders named therein. The RACC Board approved the Business Combination Agreement and the transactions contemplated thereby. The Business Combination Agreement is subject to the satisfaction or waiver of certain other closing conditions as described in the accompanying proxy statement/prospectus. There can be no assurance that the parties to the Business Combination Agreement would waive any such provision of the Business Combination Agreement if the closing conditions are not met.

Pursuant to the Business Combination Agreement: (a) at least one business day prior to the Closing Date (as defined below), (i) each outstanding RACC Class B Share will be converted, on a one-for-one basis, into a RACC Class A Share (the “Sponsor Share Conversion”) and (ii) RACC will de-register from the Register of Companies in the Cayman Islands and transfer by way of continuation from the Cayman Islands to Delaware and domesticate as a Delaware corporation in accordance with Section 388 of the General Corporation Law of the State of Delaware (the “DGCL”) and Part 12 of the Companies Act (As Revised) of the Cayman Islands (the “Domestication”), upon which RACC will change its name to “Oak Hill Bio Inc.” (“New Oak Hill Bio” or “New OHB”); and (b) RACC will acquire 100% of the issued shares in the capital of Oak Hill Bio from the Oak Hill Bio Shareholders in exchange for newly issued shares of common stock, par value $0.0001 per share, (the “New OHB Common Stock”) of New Oak Hill Bio (the “Share Acquisition”), and (c) the other transactions contemplated by the Business Combination Agreement and documents related thereto (such transactions, together with the Domestication and the Share Acquisition, the “Transactions”), all as described in more detail in the accompanying proxy statement/prospectus. The consummation of the Transactions is referred to as the “Closing” and the date of the Closing, the “Closing Date.” References herein to New Oak Hill Bio denote RACC following the Transactions.

As further described in the accompanying proxy statement/prospectus,

Certain related agreements were entered into in connection with the signing of the Business Combination Agreement, including the Sponsor Letter Agreement and the Backstop Agreement, and the parties also agreed to the forms of the Subscription Agreements, the Lock-Up Agreement, the Oak Hill Bio SAFEs and the Investor Rights Agreement (each as defined and further described in the accompanying proxy statement/prospectus). See the section entitled “Business Combination Proposal—Related Agreements” in the accompanying proxy statement/prospectus for more information.

Contemporaneously with any vote on the Transactions, public shareholders may elect to have their public shares redeemed for cash. Public shares that have been validly tendered or delivered for redemption, as described in the accompanying proxy statement/prospectus, will be redeemed prior to the Domestication. Notwithstanding the foregoing, public shareholders, together with any affiliate of his, her, its or any other person with whom he, she or it is acting in concert or as a “group” (as defined in Section 13(d)(3) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”)) will be restricted from seeking redemption rights with respect to more than 15% of the public shares. Accordingly, any public shareholders or “group” in excess of such 15% cap will not be redeemed by RACC. Any outstanding RACC Class B Shares or private placement shares of RACC (which are RACC Class A Shares) will be excluded from the pro rata calculation used to determine the per share redemption price applicable to public shares that are redeemed.

You will also be asked to consider and vote upon:

The Transactions will be consummated only if the Business Combination Proposal, the Domestication Proposal, the Governing Documents Proposal, and the Nasdaq Proposal (collectively, the “Condition Precedent Proposals”) are approved at the extraordinary general meeting. Consummation of the Transactions is not conditioned upon the approval of the Equity Incentive Plan Proposal, the Employee Stock Purchase Plan Proposal the Advisory Governing Documents Proposals or the Adjournment Proposal. Neither the Advisory Governing Documents Proposals nor the Adjournment Proposal is conditioned upon the approval of any other proposal. Each of these proposals is more fully described in the accompanying proxy statement/prospectus, which each shareholder is encouraged to read carefully and in its entirety.

The Transactions do not require approval of a majority of unaffiliated security holders because such a vote is not required under Cayman Islands law. RACC did not retain an unaffiliated representative to act solely on behalf of unaffiliated security holders for purposes of negotiating the terms of the Transactions or to prepare a report concerning the approval of the Transactions.

Only holders of record of the RACC Shares at the close of business on [●], 2026 are entitled to notice of the extraordinary general meeting and to vote and have their votes counted at the extraordinary general meeting and any adjournments of the extraordinary general meeting. The accompanying proxy statement/prospectus and proxy card are being provided to RACC’s shareholders in connection with the solicitation of proxies to be voted at the extraordinary general meeting and at any adjournment of the extraordinary general meeting. Information about the extraordinary general meeting, the Transactions and other related business to be considered by RACC’s shareholders at the extraordinary general meeting is included in the accompanying proxy statement/prospectus.

Whether or not you plan to attend the extraordinary general meeting, all of RACC’s shareholders are urged to read the accompanying proxy statement/prospectus, including the Annexes and the documents referred to therein carefully and in their entirety. You should also carefully consider the risk factors described in “Risk Factors” beginning on page 61 of the accompanying proxy statement/prospectus.

The RACC Board has received an opinion from Scalar, LLC to the effect that, as of the date of such opinion and based upon and subject to the assumptions made, procedures followed, matters considered and qualifications and limitations on the review undertaken by Scalar, LLC as set forth therein, the Closing Consideration to be issued by RACC to the Oak Hill Bio Shareholders pursuant to the Transactions is fair, from a financial point of view, to the unaffiliated holders of the RACC Class A Shares (other than (i) Oak Hill Bio and its affiliates, directors and officers, (ii) the Sponsor and Sponsor’s affiliates, directors and officers, (iii) the RACC independent directors, (iv) holders of RACC Class A Shares who elect to redeem their shares prior to or in connection with the Transaction, and (v) the PIPE Investors and their affiliates) in their capacity as holders of RACC Class A Shares. For more information, see “Business Combination Proposal—Background and Material Terms of the Transactions,” “Business Combination Proposal—Interests of RACC’s Sponsor, Directors and Officers in the Transactions” and “Business Combination Proposal—Opinion of Scalar, LLC.”

After careful consideration, the RACC Board has unanimously determined that the Transactions are in the best interests of RACC and its shareholders as a whole, unanimously approved the Business Combination Agreement and the transactions contemplated thereby, including the Share Acquisition, and unanimously recommends that RACC shareholders vote “FOR” the Business Combination Proposal, “FOR” the Domestication Proposal (in the case of the holders of RACC Class B Shares), “FOR” the Governing Documents Proposal (in the case of the holders of RACC Class B Shares), “FOR” the Advisory Governing Documents Proposals, “FOR” the Nasdaq Proposal, “FOR” the Equity Incentive Plan Proposal, “FOR” the Employee Stock Purchase Plan Proposal and “FOR” the Adjournment Proposal, in each case, if presented to the RACC shareholders at the extraordinary general meeting. The Transactions were not structured to require the approval of at least a majority of RACC’s unaffiliated shareholders because such a vote is not required under Cayman Islands law. When you consider the recommendation of these proposals by the RACC Board, you should keep in mind that RACC’s directors and officers have interests in the Transactions that may conflict with your interests as a shareholder. See the section entitled “Business Combination Proposal—Interests of RACC’s Directors and Officers, Sponsor and Others in the Transactions” in this proxy statement/prospectus for a further discussion of these considerations.

Only holders of RACC Class B Shares may vote on the Domestication Proposal and the Governing Documents Proposal and our initial shareholders hold all issued and outstanding RACC Class B Shares. The approval of each of the Domestication Proposal and the Governing Documents Proposal requires a special resolution of holders of Class B Shares, being the affirmative vote of at least a two-thirds (2/3) majority of the votes cast by the holders of the issued and outstanding RACC Class B Shares present in person or represented by proxy at the extraordinary general meeting and entitled to vote on such matter. The approval of each of the Business Combination Proposal, the Advisory Governing Documents Proposals, the Nasdaq Proposal, the Equity Incentive Plan Proposal, the Employee Stock Purchase Plan Proposal and the Adjournment Proposal requires an ordinary resolution under Cayman Islands law, being the affirmative vote of at least a majority of the votes cast by the holders of the issued and outstanding RACC Shares present in person or represented by proxy at the extraordinary general meeting and entitled to vote on such matter.

Please note that as further described in the accompanying proxy statement/prospectus, the Sponsor and the RACC independent directors have agreed to (a) vote any of their RACC Shares in favor of the Transactions and all other related proposals at the extraordinary general meeting and (b) waive their redemption rights with respect to any RACC Shares they own in connection with the consummation of the Transactions. As of the date of the accompanying proxy statement/prospectus, the initial shareholders collectively own 1,598,529 RACC Shares, or approximately 17.6% of the issued and outstanding ordinary shares as follows: (i) the Sponsor owns 1,245,269 RACC Class B Shares and 275,000 private placement shares, which are RACC Class A Shares; and (ii) the RACC independent directors each own 39,130 RACC Class B Shares, for an aggregate of 78,260 RACC Class B Shares. Pursuant to our amended and restated memorandum and articles of association, a quorum will be present

at the extraordinary general meeting if one or more shareholders who together hold not less than one-third of the issued and outstanding RACC Shares entitled to vote at the extraordinary general meeting are represented in person or by proxy at the extraordinary general meeting. Accordingly, we will need at least 1,434,314 RACC Shares, in addition to the RACC Shares held by the initial shareholders, to constitute a quorum. Approval of each of the Business Combination Proposal, the Advisory Governing Documents Proposals, the Nasdaq Proposal, the Equity Incentive Plan Proposal, the Employee Stock Purchase Plan Proposal and the Adjournment Proposal requires an ordinary resolution under Cayman Islands law, being the affirmative vote of at least a majority of the votes cast by the holders of the issued and outstanding RACC Shares present in person or represented by proxy at the extraordinary general meeting and entitled to vote on such matter. Accordingly, we will need 4,549,265 RACC Shares, or 2,950,736 public shares in addition to the RACC Shares held by the initial shareholders, to vote in favor of each of the Business Combination Proposal, the Advisory Governing Documents Proposals, the Nasdaq Proposal, the Equity Incentive Plan Proposal, the Employee Stock Purchase Plan Proposal and the Adjournment Proposal to approve it if all RACC Shares are present and cast votes. If only the minimum quorum is present, no public shares will be required to vote in favor of each of the Business Combination Proposal, the Advisory Governing Documents Proposals, the Nasdaq Proposal, the Equity Incentive Plan Proposal, the Employee Stock Purchase Plan Proposal and the Adjournment Proposal to approve it.

To ensure your representation at the extraordinary general meeting, you are urged to complete, sign, date and return the proxy card accompanying the proxy statement/prospectus as soon as possible. If your shares are held in an account at a brokerage firm or bank, you must instruct your broker or bank on how to vote your shares or, if you wish to attend the extraordinary general meeting and vote electronically, obtain a proxy from your broker or bank.

Your vote is very important regardless of the number of shares you own. Whether you plan to attend the extraordinary general meeting or not, please complete, sign, date and return the enclosed proxy card as soon as possible in the envelope provided. Your proxy card must be received by RACC not less than 48 hours before the scheduled time of the extraordinary general meeting or any adjournment thereof at which the person named in the proxy card proposes to vote. Proxy cards received after this time will not be counted. If your shares are held in “street name” or are in a margin or similar account, you should contact your broker to ensure that votes related to the shares you beneficially own are properly counted.

If you sign, date and return your proxy card without indicating how you wish to vote, your proxy will be voted FOR each of the proposals presented at the extraordinary general meeting. If you fail to return your proxy card or fail to instruct your bank, broker or other nominee how to vote, and do not attend the extraordinary general meeting in person, the effect will be, among other things, that your shares will not be counted for purposes of determining whether a quorum is present at the extraordinary general meeting. If you are a shareholder of record and you attend the extraordinary general meeting and wish to vote in person, you may withdraw your proxy and vote in person.

TO EXERCISE YOUR REDEMPTION RIGHTS, YOU MUST DEMAND IN WRITING THAT YOUR PUBLIC SHARES ARE REDEEMED FOR A PRO RATA PORTION OF THE FUNDS HELD IN THE TRUST ACCOUNT AND TENDER YOUR SHARES TO RACC’S TRANSFER AGENT AT LEAST TWO BUSINESS DAYS PRIOR TO THE INITIALLY SCHEDULED VOTE AT THE EXTRAORDINARY GENERAL MEETING. IN ORDER TO EXERCISE YOUR REDEMPTION RIGHT, YOU NEED TO IDENTIFY YOURSELF AS A BENEFICIAL HOLDER AND PROVIDE YOUR LEGAL NAME, PHONE NUMBER AND ADDRESS IN YOUR WRITTEN DEMAND. YOU MAY TENDER YOUR PUBLIC SHARES BY EITHER TENDERING OR DELIVERING YOUR PUBLIC SHARES (AND CERTIFICATES, IF ANY) AND OTHER REDEMPTION FORMS TO RACC’S TRANSFER AGENT OR BY TENDERING OR DELIVERING YOUR PUBLIC SHARES (AND CERTIFICATES, IF ANY) AND OTHER REDEMPTION FORMS ELECTRONICALLY USING THE DEPOSITORY TRUST COMPANY’S DWAC (DEPOSIT WITHDRAWAL AT CUSTODIAN) SYSTEM. IF THE BUSINESS COMBINATION IS NOT COMPLETED, THEN THESE SHARES WILL BE RETURNED TO YOU OR YOUR ACCOUNT. IF YOU HOLD THE SHARES IN STREET NAME, YOU WILL NEED TO INSTRUCT THE ACCOUNT EXECUTIVE AT YOUR BANK OR BROKER TO WITHDRAW THE SHARES FROM YOUR ACCOUNT IN ORDER TO EXERCISE YOUR REDEMPTION RIGHTS.

On behalf of the RACC Board, I would like to thank you for your support and look forward to the successful completion of the Transactions.

NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES REGULATORY AGENCY HAS APPROVED OR DISAPPROVED THE TRANSACTIONS DESCRIBED IN THE ACCOMPANYING PROXY STATEMENT/PROSPECTUS, PASSED UPON THE MERITS OR FAIRNESS OF THE BUSINESS COMBINATION OR RELATED TRANSACTIONS OR PASSED UPON THE ADEQUACY OR ACCURACY OF THE DISCLOSURE IN THE ACCOMPANYING PROXY STATEMENT/PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY CONSTITUTES A CRIMINAL OFFENSE.

The accompanying proxy statement/prospectus is dated [●], 2026 and is first being mailed to shareholders on or about [●], 2026.

RESEARCH ALLIANCE CORPORATION III

600 Fifth Avenue, 23rd Floor

New York, New York 10020

NOTICE OF EXTRAORDINARY GENERAL MEETING

TO BE HELD ON [●], 2026

TO THE SHAREHOLDERS OF RESEARCH ALLIANCE CORPORATION III:

NOTICE IS HEREBY GIVEN that an extraordinary general meeting of the shareholders (the “extraordinary general meeting”) of Research Alliance Corporation III, a Cayman Islands exempted company (“RACC”), will be held at 10:00 a.m., Eastern Time, on [●], 2026, at the offices of Cooley LLP located at 55 Hudson Yards, New York, New York 10001, and via a virtual meeting at [●], or at such other time, on such other date and at such other place to which the meeting may be adjourned.

The extraordinary general meeting will be conducted via live webcast, but the physical location of the extraordinary general meeting will remain at the location specified above for the purposes of our amended and restated memorandum and articles of association. If you wish to attend the extraordinary general meeting in person at the offices of Cooley LLP located at 55 Hudson Yards, New York, New York 10001, you must reserve your attendance at least two business days in advance of the extraordinary general meeting by contacting RACC’s secretary at RACC@racap.com by 10:00 a.m., Eastern Time, on [●], 2026. You will be able to attend the extraordinary general meeting online, vote and submit your questions during the extraordinary general meeting by visiting [●].

You are cordially invited to attend the extraordinary general meeting, which will be held for the purpose of considering and, if thought fit, passing each of the following resolutions that is put to the shareholders for a vote:

Each of the Business Combination Proposal, the Domestication Proposal, the Governing Documents Proposal, and the Nasdaq Proposal, is conditioned on the approval and adoption of each of the other Condition Precedent Proposals. Consummation of the Transactions is not conditioned upon the approval of the Equity Incentive Plan Proposal, the Employee Stock Purchase Plan Proposal the Advisory Governing Documents Proposals or the Adjournment Proposal. Neither the Advisory Governing Documents Proposals nor the Adjournment Proposal is conditioned upon the approval of any other proposal.

The Transactions do not require approval of a majority of unaffiliated security holders because such a vote is not required under Cayman Islands law. RACC did not retain an unaffiliated representative to act solely on behalf of unaffiliated security holders for purposes of negotiating the terms of the Transactions or to prepare a report concerning the approval of the Transactions.

These items of business are described in this proxy statement/prospectus, which we encourage you to read carefully and in its entirety before voting.

Only holders of record of RACC Shares at the close of business on [●], 2026 are entitled to notice of the extraordinary general meeting and to vote and have their votes counted at the extraordinary general meeting and any adjournments of the extraordinary general meeting.

This accompanying proxy statement/prospectus and accompanying proxy card are being provided to RACC’s shareholders in connection with the solicitation of proxies to be voted at the extraordinary general meeting and at any adjournment of the extraordinary general meeting. Whether or not you plan to attend the extraordinary general meeting, all of RACC’s shareholders are urged to read the accompanying proxy statement/prospectus, including the Annexes and the documents referred to therein carefully and in their entirety. You should also carefully consider the risk factors described in “Risk Factors” beginning on page 61 of this proxy statement/prospectus.

After careful consideration, the RACC Board has unanimously determined that the Transactions are in the best interests of RACC and its shareholders as a whole, unanimously approved the Business Combination Agreement and the transactions contemplated thereby, including the Share Acquisition, and unanimously recommends that RACC shareholders vote “FOR” the Business Combination Proposal, “FOR” the Domestication Proposal (in the case of the holders of RACC Class B Shares), “FOR” the Governing Documents Proposal (in the case of the holders of RACC Class B Shares), “FOR” the Advisory Governing Documents Proposal, “FOR” the Nasdaq Proposal, “FOR” the Equity Incentive Plan Proposal, “FOR” the Employee Stock Purchase Plan Proposal and “FOR” the Adjournment Proposal, in each case, if presented to the RACC shareholders at the extraordinary general meeting. The Transactions were not structured to require the approval of at least a majority of RACC’s unaffiliated shareholders because such a vote is not required under Cayman Islands law. RACC did not retain an unaffiliated representative to act solely on behalf of unaffiliated security holders for purposes of negotiating the terms of the

Transactions or to prepare a report concerning the approval of the Transactions. When you consider the recommendation of these proposals by the RACC Board, you should keep in mind that RACC’s directors and officers have interests in the Transactions that may conflict with your interests as a shareholder. See the section entitled “Business Combination Proposal—Interests of RACC’s Directors and Officers, Sponsor and Others in the Transactions” in this proxy statement/prospectus for a further discussion of these considerations.

Pursuant to the Existing Governing Documents, a public holder of the RACC Class A Shares sold in RACC’s initial public offering (whether they were purchased in RACC’s initial public offering or thereafter in the open market) (a “public shareholder,” and such shares, the “public shares”) may request to RACC to redeem its public shares for cash contemporaneously with any vote on the Transactions. If the Transactions are approved, RACC will pay to the holders of any public shares that have been validly tendered or delivered for redemption a pro rata portion of the aggregate amount then on deposit in the trust account, calculated as of two business days prior to the consummation of the Transactions and including interest earned on the funds held in the trust account not previously released to RACC for permitted withdrawals. Pursuant to the Business Combination Agreement, the Domestication shall occur at least one business day prior to the Closing Date. As a holder of public shares, you will be entitled to receive cash for any public shares to be redeemed only if you:

The redemption rights include the requirement that a holder must identify itself in writing as a beneficial holder and provide its legal name, phone number and address to Continental, RACC’s transfer agent, in order to validly redeem its shares. Public shareholders may seek to have their public shares redeemed by RACC, regardless of whether they vote for or against the Business Combination Proposal or any other proposal and whether they held RACC Shares as of the record date or acquired them after the record date. Any public shareholder who holds RACC Shares on or before [●], 2026 (two business days prior to the initially scheduled vote at the extraordinary general meeting) will have the right to demand that his, her or its public shares be redeemed for a pro rata portion of the aggregate amount then on deposit in the trust account established at the consummation of RACC’s initial public offering (the “trust account”), calculated as of two business days prior to the consummation of the Transactions and including interest earned on the funds held in the trust account not previously released to us for permitted withdrawals. For illustrative purposes, based on funds in the trust account of $75,238,468 on June 30, 2026, the estimated per share redemption price is expected to be approximately $10.03. A public shareholder who has properly tendered or delivered his, her or its public shares for redemption will be entitled to receive his, her or its pro rata portion of the aggregate amount then on deposit in the trust account in cash for such shares only if the Transactions are completed. If the Transactions are not completed, the redemptions will be canceled and the tendered shares will be returned to the relevant public shareholders as appropriate. If a public shareholder exercises its redemption rights in full, then it will be electing to exchange its public shares for cash and will no longer own shares. See “Extraordinary General Meeting of RACC—Redemption Rights” in the accompanying proxy statement/prospectus for a detailed description of the procedures to be followed if you wish to redeem your public shares for cash.

Public shareholders who seek to redeem their public shares must demand redemption no later than 5:00 p.m., Eastern Time, on [●], 2026 (two business days prior to the initially scheduled vote at the extraordinary general meeting) by (a) submitting a written request to the RACC transfer agent that RACC redeem such holder’s public shares for cash, (b) affirmatively certifying in such request to the RACC transfer agent for redemption if such holder is acting in concert or as a “group” (as defined in Section 13(d)(3) of the Exchange Act) with any other shareholder with respect to RACC Shares and (c) tendering or delivering their RACC Shares, either physically or electronically using DTC’s deposit/withdrawal at custodian system (“DWAC”), at the holder’s option, to the RACC transfer agent prior to the extraordinary general meeting. If you hold the shares in street

name, you will have to coordinate with your broker to have your shares certificated or delivered electronically. Certificates that have not been tendered or delivered to the RACC transfer agent (either physically or electronically) in accordance with these procedures will not be redeemed for cash. There is a nominal cost associated with this tendering process and the act of certificating the shares or delivering them through the DWAC system. The RACC transfer agent will typically charge the tendering broker a nominal fee and it would be up to the broker whether or not to pass this cost on to the redeeming shareholder. If the Transactions are not completed, this may result in an additional cost to shareholders for the return of their shares.

Notwithstanding the foregoing, a public shareholder, together with any affiliate of such public shareholder or any other person with whom such public shareholder is acting in concert or as a “group” (as defined in the Exchange Act), will be restricted from seeking redemption rights with respect to more than 15% of the public shares. Accordingly, any shares held by a public shareholder or “group” in excess of such 15% cap will not be redeemed by RACC.

Pursuant to that certain letter agreement, dated as of May 19, 2026, the Sponsor, officers and directors of RACC have waived all of their redemption rights and will not have redemption rights with respect to any RACC Shares owned by them, directly or indirectly. As of the date of the accompanying proxy statement/prospectus, the initial shareholders own approximately 17.6% of the issued and outstanding RACC Shares. Such shares will be excluded from the pro rata calculation used to determine the per-share redemption price. Concurrently with the execution of the Business Combination Agreement, RACC, the Sponsor, the RACC independent directors and Oak Hill Bio entered into the Sponsor Letter Agreement (the “Sponsor Letter Agreement”), pursuant to which the Sponsor and each independent director has agreed to, among other things, (i) vote in favor of the Business Combination Agreement and the Transactions, (ii) waive any adjustment to the conversion ratio set forth in the governing documents of RACC or any other anti-dilution or similar protection with respect to the RACC Class B Shares (whether resulting from the transactions contemplated by the Subscription Agreements or otherwise), (iii) be bound by certain other covenants and agreements related to the Transactions, (iv) be bound by certain transfer restrictions with respect to his or its shares in RACC prior to the closing of the Transactions, and (v) be subject to the restrictions contemplated by the Lock-Up Agreements, in each case, on the terms and subject to the conditions set forth in the Sponsor Letter Agreement. No consideration has been or will be paid to RACC, Oak Hill Bio, the Sponsor or the RACC independent directors in connection with the entry into the Sponsor Letter Agreement. See “Business Combination Proposal—Related Agreements—Investor Rights Agreement” and “Business Combination Proposal—Related Agreements—Sponsor Letter Agreement” in the accompanying proxy statement/prospectus for more information related to the Sponsor Letter Agreement and the Investor Rights Agreement.

The Business Combination Agreement is subject to the satisfaction or waiver of certain other closing conditions as described in the accompanying proxy statement/prospectus. There can be no assurance that the parties to the Business Combination Agreement would waive any such provision of the Business Combination Agreement.

The approval of each of the Domestication Proposal and the Governing Documents Proposal requires a special resolution of holders of RACC Class B Shares, being the affirmative vote of at least a two-thirds (2/3) majority of the votes cast by the holders of the issued and outstanding RACC Class B Shares present in person or represented by proxy at the extraordinary general meeting and entitled to vote on such matter. The approval of each of the Business Combination Proposal, the Advisory Governing Documents Proposals, the Nasdaq Proposal, the Equity Incentive Plan Proposal, the Employee Stock Purchase Plan Proposal and the Adjournment Proposal requires an ordinary resolution under Cayman Islands law, being the affirmative vote of at least a majority of the votes cast by the holders of the issued and outstanding RACC Shares present in person or represented by proxy at the extraordinary general meeting and entitled to vote on such matter.

Your vote is very important regardless of the number of shares you own. Whether or not you plan to attend the extraordinary general meeting, please complete, sign, date and return the enclosed proxy card as soon as possible in the envelope provided. Your proxy card must be received by RACC not less than 48 hours before the scheduled time of the extraordinary general meeting or any adjournment thereof at which the person named in

the proxy card proposes to vote. Proxy cards received after this time will not be counted. If your shares are held in “street name” or are in a margin or similar account, you should contact your broker to ensure that votes related to the shares you beneficially own are properly counted.

A RACC shareholder who is entitled to attend and vote at the extraordinary general meeting is entitled to appoint one or more proxies to attend and vote instead of that shareholder. A proxyholder need not be a RACC shareholder.

RACC reserves the right at any time to cancel the extraordinary general meeting (by means of adjourning the extraordinary general meeting sine die) and not to submit to its shareholders any of the proposals.

If you sign, date and return your proxy card without indicating how you wish to vote, your proxy will be voted FOR each of the proposals presented at the extraordinary general meeting. If you fail to return your proxy card or fail to instruct your bank, broker or other nominee how to vote, and do not attend the extraordinary general meeting in person, the effect will be, among other things, that your shares will not be counted for purposes of determining whether a quorum is present at the extraordinary general meeting. If you are a shareholder of record and you attend the extraordinary general meeting and wish to vote in person, you may withdraw your proxy and vote in person.

Your attention is directed to the remainder of the accompanying proxy statement/prospectus (including the Annexes and other documents referred to therein) for a more complete description of the proposed Transactions and related transactions and each of the proposals. You are encouraged to read the accompanying proxy statement/prospectus carefully and in its entirety, including the Annexes and other documents referred to therein. If you have any questions or need assistance voting your RACC Shares, please contact Alliance Advisors, LLC, our proxy solicitor, by calling (866) 206-8243, or banks and brokers can call collect at (973) 873-7752, or by emailing RACC@allianceadvisors.com.

Thank you for your participation. We look forward to your continued support.

By Order of the Board of Directors of Research Alliance Corporation III,

Matthew Hammond, Ph.D.

Chief Executive Officer and Director

TO EXERCISE YOUR REDEMPTION RIGHTS, YOU MUST DEMAND IN WRITING THAT YOUR PUBLIC SHARES ARE REDEEMED FOR A PRO RATA PORTION OF THE FUNDS HELD IN THE TRUST ACCOUNT AND TENDER YOUR SHARES TO RACC’S TRANSFER AGENT AT LEAST TWO BUSINESS DAYS PRIOR TO THE INITIALLY SCHEDULED VOTE AT THE EXTRAORDINARY GENERAL MEETING. IN ORDER TO EXERCISE YOUR REDEMPTION RIGHT, YOU NEED TO IDENTIFY YOURSELF AS A BENEFICIAL HOLDER AND PROVIDE YOUR LEGAL NAME, PHONE NUMBER AND ADDRESS IN YOUR WRITTEN DEMAND. YOU MAY TENDER YOUR PUBLIC SHARES BY EITHER TENDERING OR DELIVERING YOUR PUBLIC SHARES (AND CERTIFICATES, IF ANY) AND OTHER REDEMPTION FORMS TO RACC’S TRANSFER AGENT OR BY TENDERING OR DELIVERING YOUR PUBLIC SHARES (AND CERTIFICATES, IF ANY) AND OTHER REDEMPTION FORMS ELECTRONICALLY USING THE DEPOSITORY TRUST COMPANY’S DWAC (DEPOSIT WITHDRAWAL AT CUSTODIAN) SYSTEM. IF THE BUSINESS COMBINATION IS NOT COMPLETED, THEN THESE SHARES WILL BE RETURNED TO YOU OR YOUR ACCOUNT. IF YOU HOLD THE SHARES IN STREET NAME, YOU WILL NEED TO INSTRUCT THE ACCOUNT EXECUTIVE AT YOUR BANK OR BROKER TO WITHDRAW THE SHARES FROM YOUR ACCOUNT IN ORDER TO EXERCISE YOUR REDEMPTION RIGHTS.

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ADDITIONAL INFORMATION

You may request copies of this proxy statement/prospectus and any other publicly available information concerning RACC, without charge, by written request to Research Alliance Corporation III, 600 Fifth Avenue, 23rd Floor, New York, New York 10020, or by telephone request at (617) 778-2500; or Alliance Advisors, LLC, our proxy solicitor, by calling (866) 206-8243, or banks and brokers can call collect at (973) 873-7752, or by emailing RACC@allianceadvisors.com or from the SEC through the SEC website at http://www.sec.gov.

In order for RACC’s shareholders to receive timely delivery of the documents in advance of the extraordinary general meeting of RACC to be held on [●], 2026, you must request the information no later than five business days prior to the date of the extraordinary general meeting, i.e., by [●], 2026.

ABOUT THIS PROXY STATEMENT/PROSPECTUS

This document, which forms part of a registration statement on Form S-4 filed with the U.S. Securities and Exchange Commission (the “SEC”) by RACC, constitutes a prospectus of RACC under Section 5 of the U.S. Securities Act of 1933, as amended (the “Securities Act”), with respect to the shares of New OHB Common Stock to be issued to RACC shareholders, if the business combination described below is consummated. This document also constitutes a notice of meeting and a proxy statement under Section 14(a) of the Exchange Act, with respect to the extraordinary general meeting of RACC shareholders at which RACC shareholders will be asked to consider and vote upon a proposal to adopt the Business Combination Agreement and approve the Transactions by the approval and adoption of the Business Combination Proposal, among other matters.

TRADEMARKS, TRADE NAMES AND SERVICE MARKS

Oak Hill Bio and its subsidiaries own or have rights to trademarks, trade names and service marks that they use in connection with the operation of their business. In addition, Oak Hill Bio’s name, logo and website name and address are its trademarks or service marks. This document also contains references to trademarks, trade names and service marks belonging to other entities. Solely for convenience, trademarks, trade names and service marks referred to in this proxy statement/prospectus may appear without the ^® or TM symbols, but such references are not intended to indicate, in any way, that the applicable licensor will not assert, to the fullest extent under applicable law, its rights to these trademarks and trade names. We do not intend our use or display of other companies’ trade names, trademarks or service marks to imply a relationship with, or endorsement or sponsorship of us by, any other companies.

MARKET AND INDUSTRY DATA

RACC and Oak Hill Bio are responsible for the disclosure contained in this proxy statement/prospectus. However, information contained in this proxy statement/prospectus concerning the market and the industry in which Oak Hill Bio competes, including its market position, general expectations of market opportunity, size and growth rates, is based on information from various third-party sources, on assumptions made by Oak Hill Bio based on such sources and Oak Hill Bio’s knowledge of the markets for its product candidates. This information and any estimates provided herein involve numerous assumptions and limitations, and third-party sources generally state that the information contained in such source has been obtained from sources believed to be reliable. The industry in which Oak Hill Bio operates is subject to a high degree of uncertainty and risk. As a result, the estimates and market and industry information provided in this proxy statement/prospectus are subject to change based on various factors, including those described in “Cautionary Note Regarding Forward-Looking Statements” and “Risk Factors—Risks Related to Oak Hill Bio and the Transactions” and elsewhere in this proxy statement/prospectus.

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Industry publications, research, studies and forecasts generally state that the information they contain has been obtained from sources believed to be reliable, but that the accuracy and completeness of such information is not guaranteed. Although RACC and Oak Hill Bio have not independently verified the accuracy or completeness of third-party information, RACC and Oak Hill Bio believe the industry and market information included in this proxy statement/prospectus is reliable. Forecasts and other forward-looking information obtained from these sources are subject to the same qualifications and uncertainties as the other forward-looking statements in this proxy statement/prospectus. These forecasts and forward-looking information are subject to uncertainty and risk due to a variety of factors, including those described under “Risk Factors.” These and other factors could cause results to differ materially from those expressed in any forecasts or estimates.

Notwithstanding anything in this proxy statement/prospectus to the contrary, RACC and Oak Hill Bio are responsible for all disclosures in this proxy statement/prospectus.

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CURRENCY AND EXCHANGE RATES

In this proxy statement/prospectus, unless otherwise specified, all monetary amounts are in U.S. dollars and all references to “$” mean U.S. dollars. Certain monetary amounts described herein have been expressed in U.S. dollars for convenience only and, when expressed in U.S. dollars in the future, such amounts may be different from those set forth herein due to intervening exchange rate fluctuations.

PRESENTATION OF FINANCIAL INFORMATION

RACC

The historical unaudited condensed financial statements of RACC as of and for the three months ended June 30, 2026 and for the period February 19, 2026 (Inception) through June 30, 2026 and the historical audited financial statements of RACC for the period from February 19, 2026 (inception) through February 25, 2026 were prepared in accordance with accounting principles generally accepted in the U.S. (“GAAP”) and are denominated in U.S. dollars.

OHB Pediatrics Ltd. (d/b/a Oak Hill Bio)

The historical unaudited condensed financial statements of Oak Hill Bio as of and for the six months ended June 30, 2026 and the historical audited financial statements of Oak Hill Bio as of and for the years ended December 31, 2025 and 2024 were prepared in accordance with U.S. GAAP and are denominated in U.S. dollars.

Rounding and Negative Amounts

Certain numerical information and other amounts and percentages in this proxy statement/prospectus, including financial data, have been rounded. Accordingly, in certain instances, the sum of the numbers in a column or a row in tables may not conform exactly to the total figure given for that column or row or the sum of certain numbers presented as a percentage may not conform exactly to the total percentage given.

In preparing the audited historical financial statements of RACC and Oak Hill Bio, most numerical figures are presented in thousands. For the convenience of the reader of this proxy statement/prospectus, certain numerical figures in this proxy statement/prospectus are rounded to the nearest thousand. As a result of this rounding, certain numerical figures presented herein may vary slightly from the corresponding numerical figures presented in RACC’s and Oak Hill Bio’s financial statements.

The percentages presented in the textual financial disclosure in this proxy statement/prospectus are derived directly from the financial information contained in RACC’s and Oak Hill Bio’s financial statements. The percentages derived from RACC’s and Oak Hill Bio’s financial statements may be computed using the numerical figures expressed in thousands in its financial statements. Therefore, such percentages are not calculated on the basis of the financial information in the textual disclosure that has been subjected to rounding adjustments in this proxy statement/prospectus.

In tables, negative amounts are shown between parentheses. Otherwise, negative amounts may also be shown by “—” before the amount.

SELECTED DEFINITIONS

Unless otherwise stated in this proxy statement/prospectus or the context otherwise requires, references to:

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CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

Certain statements included in this proxy statement/prospectus that are not historical facts are forward-looking statements. Forward-looking statements include, but are not limited to, statements regarding our or our management team’s expectations, hopes, beliefs, intentions or strategies regarding the future, including those relating to the Transactions. The information included in this proxy statement/prospectus in relation to Oak Hill Bio has been provided by Oak Hill Bio and its respective management, and forward-looking statements include statements relating to our and its respective management team’s expectations, hopes, beliefs, intentions or strategies regarding the future, including those relating to the Transactions. In addition, any statements that refer to characterizations of future events or circumstances, including any underlying assumptions, are forward-looking statements. The words “anticipate,” “believe,” “contemplate,” “continue,” “could,” “estimate,” “expect,” “intends,” “may,” “might,” “plan,” “possible,” “potential,” “predict,” “project,” “should,” “will,” “would” and similar expressions may identify forward-looking statements, but the absence of these words does not mean that a statement is not forward-looking. Forward-looking statements in this proxy statement/prospectus may include, for example, statements about:

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The forward-looking statements contained in this proxy statement/prospectus are based on current expectations and beliefs concerning future developments and their potential effects on us and/or New Oak Hill Bio. There can be no assurance that future developments affecting us and/or New Oak Hill Bio will be those that we and/or New Oak Hill Bio have anticipated. These forward-looking statements involve a number of risks, uncertainties (some of which are beyond our control or the control of New Oak Hill Bio) or other assumptions that may cause actual results or performance to be materially different from those expressed or implied by these forward-looking statements. These risks and uncertainties include, but are not limited to, those factors described under the heading “Risk Factors.” Should one or more of these risks or uncertainties materialize, or should any of our assumptions prove incorrect, actual results may vary in material respects from those projected in these forward-looking statements. It is not possible to predict or identify all such risks. Forward-looking statements reflect Oak Hill Bio’s and our expectations, plans, or forecasts of future events and views as of the date of this proxy statement/prospectus and are qualified in their entirety by reference to the cautionary statements herein. We and Oak Hill Bio anticipate that subsequent events and developments will cause our assessments to change. These forward-looking statements should not be relied upon as representing our and Oak Hill Bio’s assessments as of any date subsequent to the date of this proxy statement/prospectus. Neither we nor Oak Hill Bio undertake any obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise, except as may be required under applicable securities laws.

Before any shareholder grants its proxy or instructs how its vote should be cast or vote on the proposals to be put to the extraordinary general meeting, such shareholder should be aware that the occurrence of the events described in the “Risk Factors” section and elsewhere in this proxy statement/prospectus may adversely affect us.

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QUESTIONS AND ANSWERS FOR SHAREHOLDERS OF RACC

The questions and answers below highlight only selected information from this document and only briefly address some commonly asked questions about the proposals to be presented at the extraordinary general meeting, including with respect to the proposed Transactions. The following questions and answers do not include all the information that is important to RACC’s shareholders. We urge shareholders to read this proxy statement/prospectus, including the Annexes and the other documents referred to herein, carefully and in their entirety to fully understand the proposed Transactions and the voting procedures for the extraordinary general meeting, which will be held at 10:00 a.m., Eastern Time, on [●], 2026, at the offices of Cooley LLP located at 55 Hudson Yards, New York, New York 10001, and via a virtual meeting at [●], or at such other time, on such other date and at such other place to which the meeting may be adjourned.

In accordance with the terms and subject to the conditions of the Business Combination Agreement, among other things:

A copy of the Business Combination Agreement is attached to this proxy statement/prospectus as Annex A and you are encouraged to read the Business Combination Agreement in its entirety.

The approval of each of the Business Combination Proposal, the Advisory Governing Documents Proposals, the Nasdaq Proposal, the Equity Incentive Plan Proposal, the Employee Stock Purchase Plan Proposal and the Adjournment Proposal requires an ordinary resolution under Cayman Islands law, being the affirmative vote of at least a majority of the votes cast by the holders of the issued and outstanding RACC Shares present in person or represented by proxy at the extraordinary general meeting and entitled to vote on such matter, and each of the Domestication Proposal and the Governing Documents Proposal requires a special resolution under Cayman Islands law, being the affirmative vote of at least two-thirds of the holders of issued and outstanding RACC Class B Shares who, being present in person or represented by proxy and entitled to vote at the extraordinary general meeting, vote at the extraordinary general meeting. The holders of the RACC Class A Shares will have no right to vote on the Domestication Proposal or the Governing Documents Proposal.

The Domestication is intended to occur at least one business day prior to the Closing Date. In connection with the Domestication, (1)(a) immediately prior to the Domestication, holders of RACC Class B Shares will convert their RACC Class B Shares into RACC Class A Shares, (b) immediately prior to the Domestication, RACC will effect public shareholder redemptions, (c) and after effecting public shareholder

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redemptions, upon the Domestication, each issued and outstanding RACC Class A Share will convert automatically by operation of law, on a one-for-one basis, into one share of New OHB Common Stock, and (2) upon the Domestication, the governing documents of RACC will become the Governing Documents as described in this proxy statement/prospectus and attached as Annex H and Annex I, respectively, to this proxy statement/prospectus, and RACC’s name will change to “Oak Hill Bio Inc.” See “Domestication Proposal.”

The provisions of the Proposed Governing Documents will differ in certain material respects from the Existing Governing Documents. Please see “What amendments will be made to the current constitutional documents of RACC?” below.

THE VOTE OF SHAREHOLDERS IS IMPORTANT. SHAREHOLDERS ARE ENCOURAGED TO VOTE AS SOON AS POSSIBLE AFTER CAREFULLY REVIEWING THIS PROXY STATEMENT/PROSPECTUS.

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Each of the Business Combination Proposal, the Domestication Proposal, the Governing Documents Proposal, and the Nasdaq Proposal is conditioned on the approval and adoption of each of the other Condition Precedent Proposals. Consummation of the Transactions is not conditioned upon the approval of the Equity Incentive Plan Proposal, the Employee Stock Purchase Plan Proposal the Advisory Governing Documents Proposals or the Adjournment Proposal. Neither the Advisory Governing Documents Proposals nor the Adjournment Proposal is conditioned upon the approval of any other proposal.

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For more information, please see “Business Combination Proposal,” “Domestication Proposal,” “Governing Documents Proposal,” “Advisory Governing Documents Proposal,” “Nasdaq Proposal,” “Equity Incentive Plan Proposal,” “Employee Stock Purchase Plan Proposal,” “Adjournment Proposal,” and “—Why is RACC proposing the Adjournment Proposal?”

RACC will hold the extraordinary general meeting to consider and vote upon these proposals. This proxy statement/prospectus contains important information about the Transactions and the other matters to be acted upon at the extraordinary general meeting. Shareholders of RACC should read it carefully.

After careful consideration, the RACC Board has unanimously determined that the Transactions are in the best interests of RACC and its shareholders, as a whole, unanimously approved the Business Combination Agreement and the transactions contemplated thereby, including the Share Acquisition, and unanimously recommends that RACC shareholders vote “FOR” the Business Combination Proposal, “FOR” the Domestication Proposal (in the case of the holders of the RACC Class B Shares), “FOR” the Governing Documents Proposal (in the case of the holders of the RACC Class B Shares), “FOR” the Advisory Governing Documents Proposal, “FOR” the Nasdaq Proposal, “FOR” the Equity Incentive Plan Proposal, “FOR” the Employee Stock Purchase Plan Proposal and “FOR” the Adjournment Proposal, in each case, if presented to the RACC shareholders at the extraordinary general meeting.

The Transactions were not structured to require the approval of at least a majority of RACC’s unaffiliated shareholders because such a vote is not required under Cayman Islands law. RACC did not retain an unaffiliated representative to act solely on behalf of unaffiliated security holders for purposes of negotiating the terms of the Transactions or to prepare a report concerning the approval of the Transactions. When you consider the recommendation of these proposals by the RACC Board, you should keep in mind that RACC’s directors and officers have interests in the Transactions that may conflict with your interests as a shareholder.

See the section entitled “Business Combination Proposal—Interests of RACC’s Directors and Executive Officers, Sponsor and Others in the Transactions” in this proxy statement/prospectus for a further discussion of these considerations.

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RACC has identified several criteria and guidelines it believes are important for evaluating acquisition opportunities. While RACC may pursue an acquisition opportunity in any business, industry, sector or geographical location, RACC intends to focus on industries that complement its management team’s background, and to capitalize on the ability of its management team to identify and acquire a business, focusing on the healthcare or healthcare-related industries, in particular companies in the drug development and commercialization, diagnostic and healthcare technology and service sectors where RACC’s management has extensive investment experience. In addition, RACC (a) must complete an initial business combination with one or more target businesses that together have a fair market value equal to at least 80% of the net assets held in the trust account (excluding deferred underwriting discounts held in trust and taxes payable on the interest earned on the trust account) at the time of the execution of a definitive agreement for an initial business combination and (b) is not permitted to effect an initial business combination with solely another blank check company or a similar company with nominal operations.

Based on its due diligence investigations of Oak Hill Bio and the industry in which it operates, including the financial and other information provided by Oak Hill Bio in the course of negotiations, the RACC Board believes that Oak Hill Bio meets the criteria and guidelines listed above. However, there is no assurance of this. See “Business Combination Proposal—RACC Board’s Reasons for the Approval of the Transactions.”

Although the RACC Board believes that the Transactions with Oak Hill Bio presents a unique business combination opportunity and is in the best interests of RACC and its shareholders, the RACC Board did consider certain potentially material negative factors in arriving at that conclusion. These factors are discussed in greater detail in the sections entitled “Business Combination Proposal—RACC Board’s Reasons for the Approval of the Transactions” and “Risk Factors—Risks Related to the Transactions and RACC.”

RACC reserves the right at any time to cancel the extraordinary general meeting (by means of adjourning the extraordinary general meeting sine die) and not to submit to its shareholders any of the proposals.

Concurrently with the execution of the Business Combination Agreement and the related ancillary documents, on July 26, 2026, the PIPE Investors executed and delivered the Subscription Agreements, which provided for binding subscriptions to purchase an aggregate of 5,500,000 shares of New OHB Common Stock and/or New OHB Pre-Funded Warrants at $10.00 per share, for aggregate gross proceeds of $55,000,000.

In evaluating the Business Combination Agreement and the Transactions, the RACC Board consulted with RACC’s management and its financial, legal and other advisors, and considered a number of factors that it believed supported its unanimous decision to approve the Business Combination Agreement and the Transactions and recommend that RACC shareholders adopt and approve the Business Combination Agreement, the Transactions and the other proposals described in this proxy statement/prospectus. These factors included, among others: Oak Hill Bio’s business, products, technology, and growth prospects; the terms of the Business Combination Agreement, including the Closing Consideration and the results of due diligence conducted by RACC’s management and advisors; the anticipated Transaction Proceeds, including the amounts expected to be available from the PIPE Financing and the trust account, as well as the availability of the Backstop Agreement to help satisfy public shareholder redemptions; the opinion of Scalar, LLC, RACC’s financial advisor, to the effect that, as of the date of such opinion and based upon and subject to the assumptions, procedures, matters and limitations set forth therein, the Closing Consideration

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to be issued to the Oak Hill Bio Shareholders pursuant to the Transactions are fair, from a financial point of view, to the unaffiliated holders of RACC Class A Shares; and the alternatives reasonably available to RACC if the Transactions were not consummated, including the risk that RACC could be required to liquidate if it did not complete an initial business combination by the required deadline.

The RACC Board also considered a number of uncertainties and risks, including the possibility that the Transactions might not be completed in a timely manner or at all, the risk that RACC’s public shareholders might redeem a substantial number of public shares, the costs and management time and effort required to complete the Transactions, and other risks described under the section entitled “Risk Factors.” After weighing these and other factors, the RACC Board unanimously determined that the potential benefits of the Transactions to RACC and its shareholders outweighed the potential risks and uncertainties. For a more complete description of the RACC Board’s reasons for the approval of the Transactions, see “Business Combination Proposal—The RACC Board’s Reasons for the Approval of the Transactions.”

Additionally, as contemplated by the Business Combination Agreement, the structure and timing of the Transactions and the PIPE Financing are consistent with common practice in initial business combination transactions consummated by special purpose acquisition companies. In addition, the timing for the consummation of the Transactions provided for in the Business Combination Agreement and the Subscription Agreements, which was effectively as soon as reasonably practicable following the execution of the Business Combination Agreement, was determined and agreed by the parties in light of general business considerations weighing in favor of consummating the transaction promptly.

For more information, see “Business Combination Proposal — Background and Material Terms of the Transactions.”

Concurrently with the execution of the Business Combination Agreement, on July 26, 2026, each of RA Capital Healthcare Fund, L.P. and RA Capital Nexus Fund IV, L.P. (the SAFE Holders) entered into the Oak Hill Bio SAFEs with Oak Hill Bio, pursuant to which the SAFE Holders provided interim financing to Oak Hill Bio in the aggregate principal amount of $45,000,000, bearing interest at a rate of 8% per annum. The Oak Hill Bio SAFEs will convert into ordinary shares of Oak Hill Bio immediately prior to the Closing, and the resulting shares will be exchanged for shares of New OHB Common Stock in the Share Acquisition, provided that if the Oak Hill Bio SAFEs remain outstanding for a period of 18 months from the date of execution, the Oak Hill Bio SAFEs will convert into OHB Series A Shares. The Oak Hill Bio SAFE Amount is added to the Base Equity Value to determine the Adjusted Equity Value for purposes of calculating the Closing Consideration.

The obligations of each party to consummate the PIPE Financing are conditioned upon, among other things, (i) the New OHB Common Stock (including the New OHB Common Stock issuable to the PIPE Investors pursuant to the Subscription Agreements) having been approved for listing on Nasdaq; and (ii) satisfaction of all conditions precedent to the closing of the transactions set forth in the Business Combination Agreement. The obligations of the PIPE Investors to consummate the PIPE Financing are further subject to additional conditions, including, among other things: (i) the Business Combination Agreement shall not have been amended, modified, or supplemented, and no condition waived thereunder, in a manner that

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would reasonably be expected to materially and adversely affect the economic benefits that a PIPE Investor would reasonably expect to receive under the Subscription Agreement; (ii) the material truth and accuracy of the representations and warranties of RACC in the Subscription Agreement, subject to customary bringdown standards; (iii) no subscription agreement, or other agreements or understandings (including side letters) entered into in connection with the sale of New OHB Common Stock and/or New OHB Pre-Funded Warrants under the Subscription Agreements, with any other PIPE Investors shall have been amended, modified, or waived in any manner that benefits such other PIPE Investor unless all PIPE Investors have been offered substantially the same benefits; and (iv) there has not occurred any material adverse effect or parent material adverse effect since the date of the Subscription Agreement that is continuing. See “Business Combination Proposal—Related Agreements—PIPE Financing.”

The Business Combination Agreement does not set out a minimum cash proceeds condition to the Closing. Instead, concurrently with the execution of the Business Combination Agreement, RACC and RA Capital Healthcare Fund, L.P. (the RA Backstop Purchaser) entered into the Backstop Agreement, pursuant to which the RA Backstop Purchaser has committed to subscribe for up to 7,500,000 shares of New OHB Common Stock at a purchase price of $10.00 per share (up to $75,000,000 in the aggregate), to the extent necessary to backstop public shareholder redemptions, such that the level of redemptions by public shareholders will not affect the dilution to public shareholders or the aggregate proceeds available to New Oak Hill Bio at Closing. See “Business Combination Proposal—Related Agreements—Backstop Agreement.”

Each U.S. stock exchange requires issuers applying for initial listing on such exchange to comply with certain initial listing criteria. New Oak Hill Bio intends to apply for listing on the Nasdaq Capital Market. In order to qualify for initial listing on the Nasdaq Capital Market, pursuant to Nasdaq Rule IM-5505, New Oak Hill Bio expects to be required to have at least 1 million unrestricted publicly held shares, a market value of unrestricted publicly held shares of at least $5 million and 300 unrestricted round lot stockholders. See the sections entitled “Adjournment Proposal” and “Risk Factors— Nasdaq may not list New Oak Hill Bio’s securities on its exchange, which could limit investors’ ability to make transactions in New Oak Hill Bio’s securities and subject New Oak Hill Bio to additional trading restrictions” for additional information.

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The “Closing Consideration” means a number of shares of New OHB Common Stock equal to (a) the Adjusted Equity Value divided by (b) $10.00. The “Adjusted Equity Value” means (a) the Base Equity Value of $160,000,000 plus (b) the Oak Hill Bio SAFE Amount. The “Exchange Ratio” means the quotient obtained by dividing (a) the Closing Consideration by (b) the number of fully-diluted Oak Hill Bio Shares outstanding as of immediately prior to the Closing (calculated as described in the Business Combination Agreement, including shares issuable upon conversion of the Oak Hill Bio SAFEs and the exercise of Company Options). At least five business days prior to the Closing Date, Oak Hill Bio is required to deliver to RACC an allocation schedule setting forth, among other things, the number of Oak Hill Bio Shares held by each Oak Hill Bio Shareholder, the Closing Consideration, the fully-diluted Oak Hill Bio Shares, the Exchange Ratio and Oak Hill Bio’s calculation of the Adjusted Equity Value. At the Closing, each outstanding Company Option will be assumed by RACC and converted into an option to purchase shares of New OHB Common Stock, with the number of shares and exercise price adjusted based on the Exchange Ratio, and will otherwise remain subject to the terms of the Oak Hill Bio Equity Incentive Plan.

Upon consummation of the Share Acquisition, Oak Hill Bio will become a wholly-owned subsidiary of RACC. See “Business Combination Proposal.”

For more details, see “Proposal No. 3—Governing Documents Proposal” and “Management of New Oak Hill Bio Following the Transactions.”

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The following table summarizes the estimated ownership of New OHB immediately following the Closing under each of the redemption scenarios described above. Because the RA Backstop Purchaser will subscribe for a number of shares equal to the number of RACC public shares redeemed, the total shares outstanding and the relative ownership of New OHB are the same under each scenario, with the interest held by RACC’s public shareholders shifting to the RA Backstop Purchaser as redemptions increase.

The estimated ownership percentages and share amounts above are preliminary and subject to change based on, among other things, the actual amount of redemptions, the final Oak Hill Bio SAFE Amount (including accrued interest through the Closing), the final Exchange Ratio, and the extent to which PIPE Investors subscribe for New OHB Pre-Funded Warrants rather than shares of New OHB Common Stock. Importantly, the Oak Hill Bio SAFEs will convert into Oak Hill Bio Shares immediately prior to the Closing, and the resulting shares will be exchanged for shares of New OHB Common Stock in the Share Acquisition. The Oak Hill Bio SAFEs are for an aggregate principal amount of $45.0 million and bear interest at a rate of 8% per annum. The sum of the principal amount of the Oak Hill Bio SAFEs and all accrued and unpaid interest thereon as of the Closing Date is referred to as the Oak Hill Bio SAFE Amount. The Oak Hill Bio SAFE Amount is added to the Base Equity Value to determine the Adjusted Equity Value for purposes of calculating the Closing Consideration. Because the unaudited pro forma condensed combined balance sheet included in this proxy statement/prospectus gives effect to the Transactions as if they had occurred on June 30, 2026, no interest is assumed to have accrued on the Oak Hill Bio SAFEs and the Oak Hill Bio SAFE Amount is assumed to equal the $45.0 million principal amount. As interest accrues, the Oak Hill Bio SAFE Amount will increase and the number of Oak Hill Bio Shares that will be issued upon conversion of the Oak Hill Bio SAFEs, as well as the corresponding number of New OHB Common Stock to be exchanged in the Share Acquisition, will increase.

The shares attributable to Oak Hill Bio’s historical shareholders and to the Oak Hill Bio SAFE holders together comprise the Closing Consideration. The table excludes the impact of any shares reserved for future issuance under New OHB’s equity incentive plans, including the New OHB Equity Incentive Plan and New OHB Employee Stock Purchase Plan described elsewhere in this proxy statement/prospectus.

For more information about the consideration to be received in the Transactions, these scenarios, and the underlying assumptions, see “Unaudited Pro Forma Combined Financial Information.” See also “Risk Factors—The public shareholders will experience dilution as a consequence of the issuance of New OHB Common Stock as consideration in the Transactions and due to future issuances of equity awards to Oak Hill Bio employees, directors, or consultants. Having a minority share position may reduce the influence that our current shareholders have on the management of New Oak Hill Bio.”

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To effect the Domestication, we will file an application for deregistration with the Cayman Islands Registrar of Companies, together with the necessary accompanying documents, and file a certificate of corporate domestication and a certificate of incorporation with the Secretary of State of the State of Delaware, under which we will be domesticated and continue as a Delaware corporation.

The approval of the Domestication Proposal is a condition to closing the Transactions under the Business Combination Agreement. The approval of the Domestication Proposal requires a special resolution of the holders of RACC Class B Shares under Cayman Islands law, being the affirmative vote of at least a two-thirds (2/3) majority of the votes cast by the holders of the issued and outstanding RACC Class B Shares who, being present in person or represented by proxy and entitled to vote at the extraordinary general meeting, vote at the extraordinary general meeting. The holders of the RACC Class A Shares will have no right to vote on the Domestication Proposal, in accordance with Article 34.2 of the Existing Governing Documents.

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RACC’s shareholders are asked to consider and vote upon and to approve as an ordinary resolution, on a non-binding and advisory basis only, six separate proposals in connection with the replacement of the Existing Governing Documents with the Proposed Governing Documents. These six proposals are being presented separately in accordance with SEC guidance to give shareholders the opportunity to present their separate views on important corporate governance provisions and will be voted upon on a non-binding advisory basis. This separate vote is not otherwise required by Cayman or Delaware law, but pursuant to SEC guidance, RACC is required to submit these provisions to its shareholders separately for approval. The shareholder votes regarding these proposals are advisory in nature, and are not binding on RACC, the RACC Board or the New OHB Board. Furthermore, the consummation of the Transactions is not conditioned on the separate approval of the Advisory Governing Documents Proposals (separate and apart from the approval of the Governing Documents Proposal). Accordingly, regardless of the outcome of the non-binding advisory vote on these proposals, RACC intends that the Proposed Governing Documents will take effect from the registration of RACC in the State of Delaware and its organization as a corporation under the laws of the State of Delaware, assuming approval of the Business Combination Proposal and the Governing Documents Proposal.

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In accordance with the terms and subject to the conditions of the Business Combination Agreement, at the Closing and following the Domestication, each of the Oak Hill Bio Shareholders will sell and transfer to RACC 100% of the issued shares in the capital of Oak Hill Bio in exchange for the Closing Consideration, consisting of shares of New OHB Common Stock, and upon consummation of the Share Acquisition, Oak Hill Bio will become a wholly-owned subsidiary of RACC. See “Business Combination Proposal.”

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Furthermore, even if the Domestication qualifies as a reorganization under Section 368(a)(1)(F) of the Code, a U.S. Holder of RACC Class A Shares may, in certain circumstances, still recognize gain (but not loss) upon the exchange of its RACC Class A Shares for shares of New OHB Common Stock pursuant to the Domestication under the passive foreign investment company (“PFIC”) rules of the Code. Provisions of the Code, its legislative history, final, temporary and proposed U.S. treasury regulations promulgated thereunder (“Treasury Regulations”) with a retroactive effective date have been promulgated under Section 1291(f) of the Code which generally require that a U.S. person who disposes of stock of a PFIC must recognize gain equal to the excess, if any, of the fair market value of the shares of New OHB Common Stock received in the Domestication over the U.S. Holder’s adjusted tax basis in the corresponding RACC Class A Shares surrendered in exchange therefor, notwithstanding any other provision of the Code. Because RACC is a blank check company with no current active business, we believe that RACC would likely to be classified as a PFIC for U.S. federal income tax purposes absent the application of an applicable exception. If the Domestication is completed in 2026, RACC believes that it is likely that it will not be classified as a PFIC because it expects to qualify for an exception to the PFIC rules known as the “start-up exception.” If the Domestication is not completed in 2026 or RACC otherwise fails to qualify for the start-up exception, the proposed Treasury Regulations, if finalized in their current form, may require a U.S. Holder of RACC Class A Shares to recognize gain on the exchange of such RACC Class A Shares for shares of New OHB Common Stock pursuant to the Domestication, unless such U.S. Holder has made certain tax elections with respect to such U.S. Holder’s RACC Class A Shares. The tax on any such gain so recognized would be imposed at the rate applicable to ordinary income and an interest charge would apply based on complex rules designed to offset the tax deferral to such U.S. Holder on the undistributed earnings, if any, of RACC. It is not possible to determine at this time whether, in what form, and with what effective date, final Treasury Regulations under Section 1291(f) of the Code will be adopted. For a more complete discussion of the potential application of the PFIC rules to U.S. Holders as a result of the Domestication, see the discussion in the section entitled “Material U.S. Federal Income Tax Considerations—Material U.S. Federal Income Tax Consequences of the Domestication to U.S. Holders—PFIC Considerations.”

Additionally, the Domestication may cause Non-U.S. Holders (as defined in “Material U.S. Federal Income Tax Considerations”) to become subject to U.S. federal withholding taxes on any dividends paid in respect of such Non-U.S. Holder’s shares of New OHB Common Stock after the Domestication.

The tax consequences of the Domestication are complex and will depend on a holder’s particular circumstances. All holders are urged to consult their tax advisor on the tax consequences to them of the Domestication, including the applicability and effect of U.S. federal, state, local and foreign income and other tax laws. For a more complete discussion of the U.S. federal income tax considerations of the Domestication, see “Material U.S. Federal Income Tax Considerations.”

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If the Share Acquisition constitutes a B Reorganization, subject to the PFIC discussion set out in greater detail in “Material U.S. Federal Income Tax Considerations—Material U.S. Federal Income Tax Consequences of the Share Acquisition to U.S. Holders”, a U.S. Holder of Oak Hill Bio Shares that receives New OHB Common Stock in exchange for Oak Hill Bio Shares in the Share Acquisition should not recognize gain or loss for U.S. federal income tax purposes as a result of the Share Acquisition. A U.S. Holder’s aggregate tax basis in the New OHB Common Stock received in exchange for Oak Hill Bio Shares surrendered in connection with the Share Acquisition should equal such U.S. Holder’s aggregate adjusted tax basis in Oak Hill Bio Shares exchanged therefor. A U.S. Holder’s holding period in the New OHB Common Stock received should include the holding period for such U.S. Holder’s shares of Oak Hill Bio Shares surrendered in exchange therefor. If a U.S. Holder has acquired different blocks of Oak Hill Bio Shares at different times or at different prices, then such U.S. Holder’s tax basis and holding period in shares of New OHB Common Stock received in the Share Acquisition generally should be determined with reference to each block of Oak Hill Bio Shares. Any such U.S. Holders should consult their tax advisors with respect to identifying the bases or holding periods of the New OHB Common Stock received in the Share Acquisition.

If, however, the Share Acquisition were determined to not qualify as a B Reorganization, then, for U.S. federal income tax purposes, a U.S. Holder generally would recognize gain or loss with respect to its Oak Hill Bio Shares in an amount equal to the difference, if any, between the fair market value (as of the closing of the Share Acquisition) of the New OHB Common Stock received pursuant to the Share Acquisition and the U.S. Holder’s tax basis in Oak Hill Bio Shares surrendered in exchange therefor. Such gain or loss generally will be a capital gain or loss. If a U.S. Holder’s holding period in Oak Hill Bio Shares surrendered in the Share Acquisition is greater than one year as of the date of the Share Acquisition, the gain or loss will be long-term capital gain or loss. Long-term capital gains of certain noncorporate holders, including individuals, are generally subject to U.S. federal income tax at preferential rates. The deductibility of capital losses is subject to limitations. Such U.S. Holder’s basis in the New OHB Common Stock would be equal to their fair market value on the date of the Share Acquisition, and such U.S. holder’s holding period for such New OHB Common Stock would begin on the day following the date of the Share Acquisition. Shareholders who hold different blocks of Oak Hill Bio Shares (generally, ordinary shares purchased or acquired on different dates or at different prices) should consult their tax advisors to determine how the above rules apply to them.

For further information, see “Material U.S. Federal Income Tax Considerations— Material U.S. Federal Income Tax Consequences of the Share Acquisition to U.S. Holders.”

All holders of Oak Hill Bio Shares should consult their tax advisors for a full understanding of the particular tax consequences of the Share Acquisition to them.

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Notwithstanding the foregoing, a public shareholder, together with any affiliate of such public shareholder or any other person with whom such public shareholder is acting in concert or as a “group” (as defined in Section 13(d)(3) of the Exchange Act), will be restricted from redeeming its public shares with respect to more than an aggregate of 15% of the public shares. Accordingly, if a public shareholder, alone or acting in concert or as a group, seeks to redeem more than 15% of the public shares, then any such shares in excess of that 15% limit would not be redeemed for cash.

The initial shareholders have agreed to waive their redemption rights with respect to all of their RACC Shares in connection with the consummation of the Transactions. Such shares will be excluded from the pro rata calculation used to determine the per-share redemption price.

Holders must complete the procedures for electing to redeem their public shares in the manner described above prior to 5:00 p.m., Eastern Time, on [●], 2026 (two business days prior to the initially scheduled vote at the extraordinary general meeting) in order for their shares to be redeemed.

The address of Continental, RACC’s transfer agent, is listed under the question “Who can help answer my questions?” below.

The redemption rights include the requirement that a holder must identify itself in writing as a beneficial holder and provide its legal name, phone number and address to RACC’s transfer agent in order to validly redeem its shares. Public shareholders may seek to have their public shares redeemed by RACC, regardless of whether they vote for or against the Business Combination Proposal or any other proposal and whether they held RACC Shares as of the record date or acquired them after the record date. Any public shareholder who holds RACC Shares on or before [●], 2026 (two business days prior to the initially scheduled vote at the extraordinary general meeting) will have the right to demand that his, her or its public shares be redeemed for a pro rata portion of the aggregate amount then on deposit in the trust account, calculated as of two business days prior to the consummation of the Transactions and including interest earned on the funds held in the trust account not previously released to us for permitted withdrawals. For illustrative purposes, based on funds in the trust account of $75,238,468 on June 30, 2026, the estimated per share redemption price is expected to be approximately $10.03. The proceeds deposited in the trust account could, however, become subject to the claims of our creditors which would have higher priority than the claims of our public shareholders. Therefore, the per share distribution from the trust account in such a situation may be less than originally expected due to such claims, and we cannot assure you that the actual per-share redemption amount received by shareholders will not be less than $10.00. While we intend to pay such amounts, if any, we cannot assure you that we will have funds sufficient to pay or provide for all creditors’ claims.

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A public shareholder who has properly tendered or delivered his, her or its public shares for redemption will be entitled to receive his, her or its pro rata portion of the aggregate amount then on deposit in the trust account in cash for such public shares only if the Transactions are completed. If the Transactions are not completed, the redemptions will be canceled, and the tendered shares will be returned to the relevant public shareholders as appropriate. If a public shareholder exercises its redemption rights in full, then it will be electing to exchange its public shares for cash and will no longer own any shares. See “Extraordinary General Meeting of RACC—Redemption Rights” in this proxy statement/prospectus for a detailed description of the procedures to be followed if you wish to redeem your public shares for cash.

Public shareholders who seek to redeem their public shares must demand redemption no later than 5:00 p.m., Eastern Time, on [●], 2026 (two business days prior to the initially scheduled vote at the extraordinary general meeting) by (a) submitting a written request to RACC’s transfer agent that RACC redeem such holder’s public shares for cash, (b) affirmatively certifying in such request to RACC’s transfer agent for redemption if such holder is acting in concert or as a “group” (as defined in Section 13(d)(3) of the Exchange Act) with any other shareholder with respect to RACC Shares and (c) tendering or delivering their RACC Shares, either physically or electronically using DTC’s DWAC system, at the holder’s option, to RACC’s transfer agent prior to the extraordinary general meeting. If you hold the RACC Shares in street name, you will have to coordinate with your broker to have your RACC Shares certificated or delivered electronically. Certificates that have not been tendered or delivered to RACC’s transfer agent (either physically or electronically) in accordance with these procedures will not be redeemed for cash. There is a nominal cost associated with this tendering process and the act of certificating the shares or delivering them through the DWAC system. RACC’s transfer agent will typically charge the tendering broker a nominal fee and it would be up to the broker whether or not to pass this cost on to the redeeming shareholder. If the Transactions are not completed, this may result in an additional cost to shareholders for the return of their RACC Shares.

Notwithstanding the foregoing, a public shareholder, together with any affiliate of his, her, its or any other person with whom he, she or it is acting in concert or as a “group” (as defined in Section 13(d)(3) of the Exchange Act) will be restricted from seeking redemption rights with respect to more than 15% of the public shares. Accordingly, any shares held by a public shareholder or “group” in excess of such 15% cap will not be redeemed by RACC.

Any request for redemption, once made by a holder of public shares, may not be withdrawn following the redemption deadline, being 5:00 p.m., Eastern Time, on [●], 2026 (two business days prior to the initially scheduled vote at the extraordinary general meeting), unless the RACC Board determines (in its sole discretion) to permit the withdrawal of such redemption request (which it may do in whole or in part). Furthermore, if a public shareholder demands redemption of such public shares and subsequently decides prior to the redemption deadline not to elect to exercise such rights, he or she may simply request that RACC’s transfer agent return the public shares (physically or electronically). Any corrected or changed written exercise of redemption rights must be received by RACC’s transfer agent prior to the vote taken on the Business Combination Proposal at the extraordinary general meeting. No request for redemption will be honored unless the holder’s public shares have been delivered (either physically or electronically) to RACC’s transfer agent at least two business days prior to the initially scheduled vote at the extraordinary general meeting.

If a public shareholder properly makes a request for redemption and the public shares are delivered as described above, then, we will redeem the public shares for a pro rata portion of the funds deposited in the trust account, calculated as of two business days prior to the consummation of the Transactions, less any taxes then due but not yet paid. If the Transactions are approved, RACC will pay to the holders of any public shares that have been validly tendered or delivered for redemption a pro rata portion of the aggregate amount then on deposit in the trust account, calculated as of two business days prior to the consummation of the Transactions and including interest earned on the funds held in the trust account not previously released to RACC for permitted withdrawals.

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If our initial business combination (which will be the Transactions should it occur) is paid for using equity or debt securities or not all of the funds released from the trust account are used for payment of the consideration in connection with our initial business combination (which will be the Transactions should it occur) or used for redemptions or purchases of the public shares, New Oak Hill Bio may apply the balance of the cash released to us from the trust account for general corporate purposes, including for maintenance or expansion of operations of New Oak Hill Bio, the payment of principal or interest due on indebtedness incurred in completing our Transactions, to fund the purchase of other companies or for working capital. See “Summary of the Proxy Statement/Prospectus—Sources and Uses of Funds for the Transactions.”

In no event will RACC redeem public shares in an amount that would cause our net tangible assets (as determined in accordance with Rule 3a51-1(g)(1) of the Exchange Act) to be less than $5,000,001 after giving effect to the transactions contemplated by the Business Combination Agreement and the PIPE Financing.

Additionally, as a result of redemptions, the trading market for the New OHB Common Stock may be less liquid than the market for the public shares was prior to consummation of the Transactions and we may not be able to meet the listing standards for Nasdaq or another national securities exchange. See “Risk Factors— Nasdaq may not list New Oak Hill Bio’s securities on its exchange, which could limit investors’ ability to make transactions in New Oak Hill Bio’s securities and subject New Oak Hill Bio to additional trading restrictions” for additional information.

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For more information about conditions to the consummation of the Transactions, see “Business Combination Proposal—Conditions to Closing of the Transactions” and “Risk Factors—If the conditions to the Business Combination Agreement are not met, the Transactions may not occur.”

RACC has applied to list the New OHB Common Stock on Nasdaq under the symbol “OAKH” upon the closing of the Transactions.

It is a condition to Oak Hill Bio’s and RACC’s obligations to consummate the Transactions that the New OHB Common Stock to be issued in connection with the Business Combination Agreement, including the shares of New OHB Common Stock in the Share Acquisition and the PIPE Shares, is approved for listing on Nasdaq, subject only to official notice of issuance. Additionally, it is a condition to the obligations of the parties to the Subscription Agreements to consummate the PIPE Financing that the New OHB Common Stock, including the PIPE Shares, has been approved for listing on Nasdaq, subject only to official notice of issuance.

RACC and Oak Hill Bio believe that RACC will satisfy the initial listing requirements of the Nasdaq Capital Market at the Closing, but there can be no assurance such listing condition will be met. If such

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listing condition is not met, the Transactions may not be consummated unless such condition is waived by Oak Hill Bio and RACC, and the PIPE Financing may not be consummated unless such condition is waived by the PIPE Investors.

However, it is important for you to consider that, at the time of the deadline for submitting redemption requests or the extraordinary general meeting, New Oak Hill Bio may not have received from Nasdaq either confirmation of the listing of the New OHB Common Stock or confirmation that approval will be obtained prior to the consummation of the Transactions, and you will not be notified prior to the deadline for submitting redemption requests or the extraordinary general meeting if New Oak Hill Bio has not yet received such approval or confirmation. As a result, you may be asked to vote to approve the Business Combination Proposal and the other proposals included in this proxy statement/prospectus without knowing whether the New OHB Common Stock will be listed on Nasdaq or another securities exchange and, further, it is possible that such listing may never be achieved and the Transactions could still be consummated if such condition is waived. Please see the subsection entitled “Description of New Oak Hill Bio Securities—Listing of Securities” for additional information.

The following table illustrates the effective underwriting discount on a percentage basis for public shares at each redemption level identified below:

Additionally, RACC engaged Leerink Partners as its exclusive financial advisor to the Transactions and RACC engaged Leerink Partners, UBS Securities LLC (“UBS”), Wells Fargo Securities, LLC (“Wells Fargo”), and LifeSci Capital LLC (“LifeSci”) as co-placement agents of the PIPE Financing. In such roles, RACC agreed to pay Leerink Partners, UBS, Wells Fargo and LifeSci in the aggregate $4.75 million at the Closing.

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Each RACC Share that you own in your name entitles you to one vote.

There are three ways to vote your RACC Shares at the extraordinary general meeting:

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Shareholders may attend the extraordinary general meeting in person. If you wish to attend the extraordinary general meeting in person, you must reserve your attendance by contacting RACC’s secretary at RACC@racap.com by 10:00 a.m., Eastern Time, on [●], 2026 (at least two business days prior to the extraordinary general meeting). You can participate in the meeting, vote, and submit questions via live webcast by visiting [●].

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You can pre-register to attend the virtual extraordinary general meeting starting [●], 2026 at 9:30 a.m., Eastern Time (three business days prior to the meeting date). Enter the URL address [●] into your browser, enter your control number, name and email address. Once you pre-register you can vote or enter questions in the chat box. At the start of the extraordinary general meeting, you will need to log in again using your control number and will also be prompted to enter your control number if you vote during the extraordinary general meeting.

Shareholders who hold their investments through a bank or broker, will need to contact RACC’s transfer agent to receive a control number. If you plan to vote at the extraordinary general meeting you will need to have a legal proxy from your bank or broker or if you would like to join and not vote, RACC’s transfer agent will issue you a guest control number with proof of ownership. In either case you must contact RACC’s transfer agent for specific instructions on how to receive the control number. RACC’s transfer agent can be contacted at the number or email address above. Please allow up to 72 hours prior to the meeting for processing your control number.

If you do not have Internet access, you can listen only to the meeting by dialing [●] (toll-free) (or [●] if you are located outside the U.S. and Canada (standard rates apply)) and when prompted enter the pin number [●]. Please note that you will not be able to vote or ask questions at the extraordinary general meeting if you choose to participate telephonically, and your participation on this basis will not count towards quorum.

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As of the close of business on the record date, there were 9,098,529 RACC Shares issued and outstanding, of which 7,775,000 were RACC Class A Shares and 1,323,529 were RACC Class B Shares. The initial shareholders collectively own 1,598,529 RACC Shares, or approximately 17.6% of the issued and outstanding ordinary shares as follows: (i) the Sponsor owns 1,245,269 RACC Class B Shares and 275,000 RACC Class A Shares; and (ii) the RACC independent directors (Messrs. MacLean and Miller) each own 39,130 RACC Class B Shares, for an aggregate of 78,260 RACC Class B Shares. Pursuant to our amended and restated memorandum and articles of association, a quorum will be present at the extraordinary general meeting if one or more shareholders who together hold not less than one-third of the issued and outstanding RACC Shares entitled to vote at the extraordinary general meeting are represented in person or by proxy at the extraordinary general meeting. Accordingly, we will need at least 1,434,314 RACC Shares, in addition to the RACC Shares held by the initial shareholders, to constitute a quorum. Approval of each of the Business Combination Proposal, the Advisory Governing Documents Proposals, the Nasdaq Proposal, the Equity Incentive Plan Proposal, the Employee Stock Purchase Plan Proposal and the Adjournment Proposal requires an ordinary resolution under Cayman Islands law, being the affirmative vote of at least a majority of the votes cast by the holders of the issued and outstanding RACC Shares present in person or represented by proxy at the extraordinary general meeting and entitled to vote on such matter. Accordingly, we will need 4,549,265 RACC Shares, or 2,950,736 public shares in addition to the RACC Shares held by the initial shareholders, to vote in favor of each of the Business Combination Proposal, the Advisory Governing Documents Proposals, the Nasdaq Proposal, the Equity Incentive Plan Proposal, the Employee Stock Purchase Plan Proposal and the Adjournment Proposal to approve it if all RACC Shares are present and cast votes. If only the minimum quorum is present, no public shares will be required to vote in favor of each of the Business Combination Proposal, the Advisory Governing Documents Proposals, the Nasdaq Proposal, the Equity Incentive Plan Proposal, the Employee Stock Purchase Plan Proposal and the Adjournment Proposal to approve it.

Approval of the Domestication Proposal and the Governing Documents Proposal requires a special resolution of the holders of RACC Class B Shares under Cayman Islands law, being the affirmative vote of at least two-thirds of the holders of issued and outstanding RACC Class B Shares who, being present in person or represented by proxy and entitled to vote at the extraordinary general meeting, vote at the extraordinary general meeting. The holders of the RACC Class A Shares will have no right to vote on the Domestication Proposal or the Governing Documents Proposal.

The existence of financial and personal interests of one or more of RACC’s directors may result in a conflict of interest on the part of such director(s) between what he or they may believe is in the best interests of RACC and its shareholders, as a whole, and what he or they may believe is best for himself or themselves in determining to recommend that shareholders vote for the proposals. In addition, RACC’s officers have interests in the Transactions that may conflict with your interests as a shareholder. See the section entitled

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“Business Combination Proposal—Interests of RACC’s Directors and Executive Officers in the Transactions” for a further discussion of these considerations.

In the event our Sponsor, the other initial shareholders and/or any of their respective affiliates, subject to Rule 14e-5 under the Exchange Act, purchase public shares in privately negotiated transactions from public shareholders who have already elected to exercise their redemption rights, such selling shareholder would be required to revoke their prior elections to redeem their public shares. Any public shares purchased by our Sponsor, the other initial shareholders or any of their respective affiliates would not be voted in favor of the Condition Precedent Proposals, and redemptions rights (if any) over such purchased securities would be waived by the aforementioned persons. Any such purchased securities would also have a purchase price no higher than the redemption price.

In addition, we will file a Current Report on Form 8-K and will (i) amend this proxy statement/prospectus, if such arrangements are entered into prior to effectiveness of the registration statement on Form S-4 of which this proxy statement/prospectus forms a part, or (ii) file a supplement to this proxy statement/prospectus, if such arrangements are entered into after effectiveness of such registration statement, to disclose any arrangements entered into or significant purchases made by any of the aforementioned persons that would affect the vote on the Condition Precedent Proposals or the satisfaction of any closing conditions. Any such disclosures will include descriptions of any arrangements entered into or significant purchases by any of the aforementioned persons, and will describe the material costs of such arrangements to RACC and Oak Hill Bio, as well as their potential impact to New Oak Hill Bio after giving effect to the Transactions as well as: (i) the number of public shares purchased outside of the redemption offer, along with the purchase price(s) for such shares; (ii) the purpose of any such purchases; (iii) the impact, if any, of the purchases on the likelihood that the Condition Precedent Proposals will be approved; (iv) the identities of the equity holders who sold to our Sponsor, the other initial shareholders or their respective affiliates (if not purchased on the open market) or the nature of the equity holders (e.g., 5% security holders) who sold such public shares; and

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(v) the number of public shares for which RACC has received redemption requests pursuant to our redemption offer. None of the funds in the trust account will be used to purchase public shares in such transactions. None of our Sponsor, the other initial shareholders nor any of their respective affiliates will make any such purchases when they are in possession of any material non-public information not disclosed to the seller of such public shares or during a restricted period under Regulation M under the Exchange Act. RACC hereby represents that any public shares purchased by our Sponsor, the other initial shareholders or any of their respective affiliates in situations in which the tender offer rules regarding restrictions on purchases would apply would not be voted in favor of approving the Condition Precedent Proposals.

The Sponsor is an affiliate of RA Capital Management, a leading life sciences focused investment firm with over $15 billion of regulatory assets under management as of December 31, 2025. Since its launch in 2002, RA Capital Management has focused primarily on the healthcare industry. Matthew Hammond, PhD, RACC’s Chief Executive Officer and Director, is a Partner on the investment team at RA Capital Management, and Henry Stusnick, RACC’s Chief Business Officer and Chief Operating Officer, is an Analyst on the investment team at RA Capital Management. For a description of our management team’s previous experience with other special purpose acquisition vehicles, see “Information about RACC—Experience with Special Purpose Acquisition Vehicles.”

The Sponsor is organized in the Cayman Islands as a limited liability company for the purpose of holding securities in RACC. The Sponsor’s equity owners are investment funds affiliated with RA Capital Management, L.P. Matthew Hammond is the sole director and Manager of the Sponsor and, as such, has voting and investment discretion with respect to the securities held of record by the Sponsor and may be deemed to have beneficial ownership of the securities held directly by the Sponsor. Mr. Hammond disclaims beneficial ownership of the securities held by the Sponsor except to the extent of his pecuniary interest therein, if any.

The Sponsor is not “controlled” (as defined in 31 CFR 800.208) by a foreign person, such that the Sponsor’s involvement in any business combination would be a “covered transaction” (as defined in 31 CFR 800.213). However, it is possible that non-U.S. persons could be involved in our business combination, which may increase the risk that our business combination becomes subject to regulatory review, including review by the Committee on Foreign Investment in the U.S. (“CFIUS”), and that restrictions, limitations or conditions will be imposed by CFIUS. If our business combination with a U.S. business is subject to CFIUS review, the scope of which was expanded by FIRRMA, to include certain non-passive, non-controlling investments in sensitive U.S. businesses and certain acquisitions of real estate even with no underlying U.S. business. FIRRMA, and subsequent implementing regulations that are now in force, also subjects certain categories of investments to mandatory filings. If our potential business combination with a U.S. business falls within CFIUS’s jurisdiction, we may determine that we are required to make a mandatory filing or that we will submit a voluntary notice to CFIUS, or to proceed with a business combination without notifying CFIUS and risk CFIUS intervention, before or after closing a business combination. CFIUS may decide to block or delay our business combination, impose conditions to mitigate national security concerns with respect to such business combination or order us to divest all or a portion of a U.S. business of the combined company without first obtaining CFIUS clearance, which may limit the attractiveness of 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 a 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. A failure to notify CFIUS of a transaction where such notification was required or otherwise warranted based on the national

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security considerations presented by an investment target may expose our Sponsor and/or the combined company to legal penalties, costs, and/or other adverse reputational and financial effects, thus potentially diminishing the value of the combined company. In addition, CFIUS is actively pursuing transactions that were not notified to it and may ask questions regarding, or impose restrictions or mitigation on, a business combination post-closing.

Moreover, the process of government review, whether by the CFIUS or otherwise, could be lengthy and we have limited time to complete our business combination. If we cannot complete a business combination within 24 months from the closing of our Initial Public Offering because the transaction is still under review or because our business combination is ultimately prohibited by CFIUS or another U.S. government entity, we may be required to liquidate. If we liquidate, shareholders of record may only receive their pro rata portion of funds available in the trust account. This will also cause you 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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In addition, certain persons who are expected to join the New OHB Board after the completion of the Transactions may have interests in the Transactions that are different from, or in addition to, the interests of the RACC shareholders. See “Proposal 1: Business Combination Proposal—Interests of Oak Hill Bio Directors and Executive Officers in the Transactions” for more information.

If your shares are held in “street name” by your broker, bank or another nominee, you must contact your broker, bank or other nominee to change your vote.

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Alliance Advisors, LLC

150 Clove Road

Suite 400

Little Falls, NJ 07424

Individuals, please call: (866) 206-8243

Banks and brokerage firms, please call: (973) 873-7752

Email: RACC@allianceadvisors.com

You also may obtain additional information about RACC from documents filed with the SEC by following the instructions in the section entitled “Where You Can Find More Information; Incorporation by Reference.” If you are a holder of public shares and you intend to seek redemption of your public shares, you will need to tender or deliver your public shares (and share certificates (if any) and other redemption forms) (either physically or electronically) to the RACC transfer agent, at the address below prior to 5:00 p.m., Eastern Time, on [●], 2026 (two business days prior to the initially scheduled vote at the extraordinary general meeting). If you have questions regarding the certification of your position or delivery of your stock, please contact:

Continental Stock Transfer & Trust Company

One State Street Plaza, 30th Floor

New York, New York 10004

Attention: SPAC Redemption Team

E-mail: spacredemptions@continentalstock.com

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