Bleichroeder Acquisition Corp. II reports that Adage Capital Management, L.P. and affiliated reporting persons each beneficially hold 2,250,000 Class A ordinary shares, representing 7.83% of the class based on 28,750,000 shares outstanding as of March 16, 2026.
The Schedule 13G states the shares are directly held by Adage Capital Partners, L.P. and that voting and dispositive power is shared; filing signatures are by Robert Atchinson and Phillip Gross dated May 13, 2026.
Positive
None.
Negative
None.
Insights
Adage holds a meaningful passive stake in BBCQ under beneficial ownership rules.
Adage Capital Management, ACP and associated managers each report beneficial ownership of 2,250,000 shares, equal to 7.83% of the class using the disclosed March 16, 2026 outstanding base. The filing is a standard Schedule 13G disclosure of passive ownership.
Key dependencies are the disclosed shared voting and shared dispositive powers and the reference to the Company’s Form 10-K for the outstanding share count. Subsequent filings could update the percentage if outstanding shares change.
Filing clarifies attribution and entity relationships among Adage, ACP and individual managers.
The statement attributes the shares to Adage Capital Partners, L.P., with Messrs. Atchinson and Gross identified as managing members of related entities that exercise investment management roles. The joint filing agreement is included as Exhibit 99.1.
The disclosure emphasizes shared control rather than sole authority; any change in voting or disposition arrangements should appear in later SEC filings.
Key Figures
Shares beneficially owned:2,250,000 sharesPercent of class:7.83%Shares outstanding (source):28,750,000 shares
3 metrics
Shares beneficially owned2,250,000 sharesreported per Reporting Person
Percent of class7.83%based on 28,750,000 shares outstanding as of March 16, 2026
Shares outstanding (source)28,750,000 sharesas of March 16, 2026 per Form 10-K
Key Terms
Schedule 13G, beneficially owned, shared dispositive power
3 terms
Schedule 13Gregulatory
"Item 2(a) This statement is filed by: (i) Adage Capital Management, L.P."
A Schedule 13G is a formal document that investors file with the government when they acquire a large ownership stake in a company, usually for investment purposes rather than control. It helps keep the public informed about who owns significant parts of a company's shares, which can influence how the company is managed and how investors make decisions. Filing this schedule is important for transparency and understanding the ownership landscape of publicly traded companies.
beneficially ownedregulatory
"Item 4(a) Amount beneficially owned: The information required by Item 4(a) is set forth in Row 9"
Beneficially owned describes securities or assets where a person has the economic rights and control—such as the right to receive dividends and to direct voting—even if legal title is held in another name. Think of it like having the keys and using a car that’s registered to someone else: you get the benefits and make decisions. Investors care because beneficial ownership reveals who truly controls value and voting power, affecting corporate decisions and takeover dynamics.
shared dispositive powerregulatory
"Row 8 | Shared Dispositive Power 2,250,000.00"
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
UNDER THE SECURITIES EXCHANGE ACT OF 1934
Bleichroeder Acquisition Corp. II
(Name of Issuer)
Class A ordinary shares, par value $0.0001 per share
(Title of Class of Securities)
G1170E104
(CUSIP Number)
03/31/2026
(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):
G1170E104
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
2,250,000.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
2,250,000.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
2,250,000.00
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)
7.83 %
12
Type of Reporting Person (See Instructions)
IA, PN
SCHEDULE 13G
CUSIP Number(s):
G1170E104
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
2,250,000.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
2,250,000.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
2,250,000.00
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)
7.83 %
12
Type of Reporting Person (See Instructions)
HC, IN
SCHEDULE 13G
CUSIP Number(s):
G1170E104
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
2,250,000.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
2,250,000.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
2,250,000.00
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)
7.83 %
12
Type of Reporting Person (See Instructions)
HC, IN
SCHEDULE 13G
Item 1.
(a)
Name of issuer:
Bleichroeder Acquisition Corp. II
(b)
Address of issuer's principal executive offices:
1345 Avenue of the Americas, Fl 47, New York NY 10105
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 Bleichroeder Acquisition Corp. II, 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):
G1170E104
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 28,750,000 Class A Ordinary Shares outstanding as of March 16, 2026, as reported in the Company's Annual Report on Form 10-K for the year ended December 31, 2025, filed with the Securities and Exchange Commission on March 16, 2026.
(b)
Percent of class:
7.83%
(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
What stake does Adage Capital report in Bleichroeder Acquisition Corp. II (BBCQ)?
Adage Capital reports beneficial ownership of 2,250,000 Class A shares, representing 7.83% of the class based on March 16, 2026 outstanding share count.
How was the 7.83% ownership percentage calculated for BBCQ?
The percentage is calculated using an aggregate of 28,750,000 Class A Ordinary Shares outstanding as of March 16, 2026, per the company’s Form 10-K referenced in the filing.
Who are the reporting persons named in the Schedule 13G for BBCQ?
The filing is by Adage Capital Management, L.P., and individuals Robert Atchinson and Phillip Gross, acting in managerial roles for related entities and signing the statement on May 13, 2026.
Does the Schedule 13G indicate sole voting or dispositive power for Adage?
No; the filing shows 0 sole voting and dispositive power and reports shared voting and shared dispositive power over the 2,250,000 shares.
What document confirms the outstanding share count used in the Schedule 13G calculation?
The filing cites the Company’s Annual Report on Form 10-K for the year ended December 31, 2025 filed on March 16, 2026 as the source for the 28,750,000 outstanding shares figure.
