Adage group discloses 5.68% OHAC stake in Oceanhawk Acquisition Corp. (OHAC)

Rhea-AI Filing Summary

Oceanhawk Acquisition Corp. has a significant shareholder group led by Adage Capital Management, L.P. and its principals Robert Atchinson and Phillip Gross. These reporting persons collectively report beneficial ownership of 1,075,000 Class A Ordinary Shares of Oceanhawk Acquisition Corp.

This position represents 5.68% of the 18,930,000 Class A Ordinary Shares outstanding, based on the company’s referenced prospectus and current report after completion of the offering, private placement and full exercise of the underwriters' over-allotment option. The reporting persons have shared voting and shared dispositive power over all 1,075,000 shares, and no sole voting or dispositive power.

Key Figures

Shares beneficially owned: 1,075,000 Class A Ordinary Shares Ownership percentage: 5.68% Shares outstanding: 18,930,000 Class A Ordinary Shares +2 more

5 metrics

Shares beneficially owned 1,075,000 Class A Ordinary Shares Beneficial ownership reported by the Adage reporting persons

Ownership percentage 5.68% Percentage of Oceanhawk Class A Ordinary Shares outstanding held by reporting persons

Shares outstanding 18,930,000 Class A Ordinary Shares Aggregate outstanding shares used to calculate 5.68% ownership

Shared voting power 1,075,000 shares Shares over which reporting persons have shared voting power

Shared dispositive power 1,075,000 shares Shares over which reporting persons have shared dispositive power

Key Terms

beneficial ownership, shared voting power, shared dispositive power, over-allotment option, +1 more

5 terms

beneficial ownership financial

"as to beneficial ownership of the securities reported herein"

Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.

shared voting power financial

"Shared Voting Power 1,075,000.00"

Shared voting power occurs when two or more parties jointly have the right to vote or decide how a block of company shares is cast, like co-owners who must agree before moving a piece of furniture. Investors care because who controls voting rights affects board elections, major corporate decisions and takeover outcomes, and shared control can alter regulatory disclosures and the practical influence any holder has over a company’s direction and value.

shared dispositive power financial

"Shared Dispositive Power 1,075,000.00"

over-allotment option financial

"full exercise of the underwriters' over-allotment option, all as described therein"

An over-allotment option is a special agreement that allows underwriters to sell more shares than initially planned if demand is high. Think of it like a retailer offering extra units of a popular product to meet additional customer interest. This option helps ensure the full sale is completed and can also give investors extra shares if they want more.

CUSIP financial

"CUSIP Number(s): G6722R107"

A CUSIP is a nine-character alphanumeric code that uniquely identifies a U.S. or Canadian financial security—such as a stock, bond, or fund share—like a Social Security number for an investment. It matters to investors because brokers, exchanges and record-keepers use the CUSIP to match trades, track ownership, settle transactions and pull accurate records, reducing errors and ensuring money and securities go to the right place.

FAQ

What percentage of Oceanhawk Acquisition Corp. (OHAC) does Adage Capital report owning?

Adage Capital and its principals report beneficial ownership of 5.68% of Oceanhawk Acquisition Corp.’s Class A Ordinary Shares, based on 18,930,000 shares outstanding after the offering, private placement and full over-allotment exercise.

How many Oceanhawk Acquisition Corp. (OHAC) shares are held by the reporting persons?

The reporting persons beneficially own 1,075,000 Class A Ordinary Shares of Oceanhawk Acquisition Corp., all held through Adage Capital Partners, L.P., with shared voting and shared dispositive power over these shares.

Who are the reporting persons on this Schedule 13G for OHAC?

The reporting persons are Adage Capital Management, L.P., and individuals Robert Atchinson and Phillip Gross, who file as investment manager and managing members related to Adage Capital Partners, L.P., which directly holds the Class A Ordinary Shares.

What is the total number of OHAC Class A shares used to calculate Adage’s 5.68% stake?

The 5.68% ownership figure is calculated using 18,930,000 Class A Ordinary Shares outstanding, as referenced from Oceanhawk Acquisition Corp.’s prospectus and current report after the offering, private placement and full over-allotment exercise.

Do the Adage reporting persons have sole or shared voting power over OHAC shares?

The reporting persons have 0 shares with sole voting or dispositive power and 1,075,000 shares with shared voting and shared dispositive power over Oceanhawk Acquisition Corp.’s Class A Ordinary Shares.

AI-generated analysis. How Rhea-AI works. Not financial advice.

See more from StockTitan in Google Search and AI answers. Adds StockTitan as a preferred source · opens Google

Add on Google Not now

Available on EDGAR 08/12/2026 - 12:05 PM Accepted by SEC EDGAR 08/12/2026 - 12:04 PM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

Oceanhawk Acquisition Corp.

(Name of Issuer)

Class A Ordinary Shares, par value $0.0001 per share

(Title of Class of Securities)

G6722R107

(CUSIP Number)

06/30/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): G6722R107

1

Names of Reporting Persons

Adage Capital Management, L.P.

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 1,075,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,075,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,075,000.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

5.68 %

12

Type of Reporting Person (See Instructions)

IA, PN

SCHEDULE 13G

CUSIP Number(s): G6722R107

1

Names of Reporting Persons

Robert Atchinson

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 1,075,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,075,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,075,000.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

5.68 %

12

Type of Reporting Person (See Instructions)

HC, IN

SCHEDULE 13G

CUSIP Number(s): G6722R107

1

Names of Reporting Persons

Phillip Gross

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 1,075,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,075,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,075,000.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

5.68 %

12

Type of Reporting Person (See Instructions)

HC, IN

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Oceanhawk Acquisition Corp.
(b)	Address of issuer's principal executive offices: 712 Fifth Avenue, 36th Floor, New York, NY 10019
Item 2.
(a)	Name of person filing: This statement is filed by: (i) Adage Capital Management, L.P., a Delaware limited partnership ("ACM"), as the investment manager of Adage Capital Partners, L.P., a Delaware limited partnership ("ACP"), with respect to the Class A ordinary shares, par value $0.0001 per share ("Class A Ordinary Shares") of Oceanhawk Acquisition Corp., a Cayman Islands exempted company (the "Company") directly held by ACP; (ii) Robert Atchinson ("Mr. Atchinson"), as (1) managing member of Adage Capital Advisors, L.L.C., a limited liability company organized under the laws of the State of Delaware ("ACA"), managing member of Adage Capital Partners GP, L.L.C., a limited liability company organized under the laws of the State of Delaware ("ACPGP"), general partner of ACP, and (2) managing member of Adage Capital Partners, L.L.C., a Delaware limited liability company ("ACPLLC"), general partner of ACM, with respect to the Class A Ordinary Shares directly held by ACP; and (iii) Phillip Gross ("Mr. Gross"), as (1) managing member of ACA, managing member of ACPGP, and (2) managing member of ACPLLC, general partner of ACM, with respect to the Class A Ordinary Shares directly held by ACP. The foregoing persons are hereinafter sometimes collectively referred to as the "Reporting Persons." Any disclosures herein with respect to persons other than the Reporting Persons are made on information and belief after making inquiry to the appropriate party. The filing of this statement should not be construed in and of itself as an admission by any Reporting Person as to beneficial ownership of the securities reported herein.
(b)	Address or principal business office or, if none, residence: The address of the business office of each of the Reporting Persons is 200 Clarendon Street, 52nd Floor, Boston, Massachusetts 02116.
(c)	Citizenship: ACM is a limited partnership organized under the laws of the State of Delaware. Messrs. Gross and Atchinson are citizens of the United States.
(d)	Title of class of securities: Class A Ordinary Shares, par value $0.0001 per share
(e)	CUSIP Number(s): G6722R107
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: The information required by Item 4(a) is set forth in Row 9 of the cover page for each of the Reporting Persons and is incorporated herein by reference. The percentage set forth in this Schedule 13G is calculated based upon an aggregate of 18,930,000 Class A Ordinary Shares outstanding, as reported in the Company's Prospectus filed pursuant to Rule 424(b)(4) with the Securities and Exchange Commission on May 22, 2026 and the Company's Current Report on Form 8-K filed with the Securities and Exchange Commission on June 4, 2026, after giving effect to the completion of the offering, the consummation of the simultaneous private placement and the full exercise of the underwriters' over-allotment option, all as described therein.
(b)	Percent of class: 5.68%
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: The information required by Item 4(c)(i) is set forth in Row 5 of the cover page for each of the Reporting Persons and is incorporated herein by reference.
	(ii) Shared power to vote or to direct the vote: The information required by Item 4(c)(ii) is set forth in Row 6 of the cover page for each of the Reporting Persons and is incorporated herein by reference.
	(iii) Sole power to dispose or to direct the disposition of: The information required by Item 4(c)(iii) is set forth in Row 7 of the cover page for each of the Reporting Persons and is incorporated herein by reference.
	(iv) Shared power to dispose or to direct the disposition of: The information required by Item 4(c)(iv) is set forth in Row 8 of the cover page for each of the Reporting Persons and is incorporated herein by reference.
Item 5.	Ownership of 5 Percent or Less of a Class.
	Not Applicable
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required. See Item 2(a).
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Adage Capital Management, L.P.

Signature:	/s/ Robert Atchinson
Name/Title:	By: Adage Capital Partners, L.L.C., its General Partner, By: Robert Atchinson, its Managing Member
Date:	08/12/2026

Robert Atchinson

Signature:	/s/ Robert Atchinson
Name/Title:	Robert Atchinson, individually
Date:	08/12/2026

Phillip Gross

Signature:	/s/ Phillip Gross
Name/Title:	Phillip Gross, individually
Date:	08/12/2026

Comments accompanying signature: Exhibit 99.1: Joint Filing Agreement