Bleichroeder Reports 1.61% Stake in Aptose in Schedule 13G/A

Rhea-AI Filing Summary

Aptose Biosciences Inc. is the issuer named in this Schedule 13G/A amendment reporting that Bleichroeder LP, Bleichroeder Holdings LLC and Andrew Gundlach beneficially own 41,666 common shares, representing 1.61% of the outstanding common stock (CUSIP 03835T309). The filing shows the reporting persons have sole voting and sole dispositive power over the 41,666 shares and states the shares were acquired and are held in the ordinary course of business, not for the purpose of changing or influencing control. The filing identifies Bleichroeder LP as an investment adviser registered under Section 203 and notes clients retain the right to dividends or sale proceeds. Signatures are dated 08/12/2025.

Positive

• Clear disclosure of beneficial ownership: 41,666 shares (1.61%)
• Certifies ordinary-course holding and not acquired to influence control

Negative

• None.

Insights

Financial Analyst

Minor passive stake disclosed; limited direct market impact.

The filing documents a 1.61% beneficial position of 41,666 Aptose shares held by Bleichroeder-affiliated entities and Andrew Gundlach with sole voting and dispositive power. Because the position is below 5% and the filer certifies the holdings are in the ordinary course of business and not intended to influence control, this disclosure is primarily transparency-focused rather than indicative of a strategic stake or control intent. Investors gain clarity on ownership concentration but should not infer activist intentions from this filing alone.

Corporate Governance Expert

Disclosure aligns with regulatory requirements; governance implications appear limited.

The Schedule 13G/A identifies Bleichroeder LP as an SEC-registered investment adviser and clarifies clients retain economic rights to dividends and sale proceeds. The signatory certifies ordinary-course ownership and absence of control-seeking purpose, which reduces immediate governance concerns. The reporting of sole voting and dispositive power is relevant for record-keeping, but at 1.61% the position is not material for board or control dynamics under typical thresholds.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 4)

Aptose Biosciences Inc.

(Name of Issuer)

Common Shares

(Title of Class of Securities)

03835T309

(CUSIP Number)

06/30/2025

(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)

SCHEDULE 13G

CUSIP No. 03835T309

1

Names of Reporting Persons

Bleichroeder LP

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 41,666.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 41,666.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

41,666.00

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)

1.61 %

12

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13G

CUSIP No. 03835T309

1

Names of Reporting Persons

Bleichroeder Holdings LLC

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 41,666.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 41,666.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

41,666.00

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)

1.61 %

12

Type of Reporting Person (See Instructions)

HC

SCHEDULE 13G

CUSIP No. 03835T309

1

Names of Reporting Persons

Andrew Gundlach

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 41,666.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 41,666.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

41,666.00

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)

1.61 %

12

Type of Reporting Person (See Instructions)

HC

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Aptose Biosciences Inc.
(b)	Address of issuer's principal executive offices: 66 WELLINGTON STREET WEST, SUITE 5300, TD BANK TOWER BOX 48, TORONTO, A6 M5K 1E6
Item 2.
(a)	Name of person filing: Bleichroeder Holdings LLC Bleichroeder LP Andrew Gundlach
(b)	Address or principal business office or, if none, residence: 1345 Avenue of the Americas, 47th Floor New York, NY 10105
(c)	Citizenship: Bleichroeder Holdings LLC and Bleichroeder LP: Delaware, USA Andrew Gundlach: United States
(d)	Title of class of securities: Common Shares
(e)	CUSIP No.: 03835T309
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: See cover page.
(b)	Percent of class: See cover page.
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: See cover page.
	(ii) Shared power to vote or to direct the vote: See cover page.
	(iii) Sole power to dispose or to direct the disposition of: See cover page.
	(iv) Shared power to dispose or to direct the disposition of: See cover page.
Item 5.	Ownership of 5 Percent or Less of a Class.
	Ownership of 5 percent or less of a class
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. Bleichroeder LP ("Bleichroeder"), an investment adviser registered under Section 203 of the Investment Advisers Act of 1940, is deemed to be the beneficial owner of 41,666 shares, or 1.61% of the common stock believed to be outstanding as a result of acting as investment adviser to various clients. Clients of Bleichroeder have the right to receive and the ultimate power to direct the receipt of dividends from, or the proceeds of the sale of, such securities.
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	If a parent holding company has filed this schedule, pursuant to Rule 13d-1(b)(ii)(G), so indicate under Item 3(g) and attach an exhibit stating the identity and the Item 3 classification of the relevant subsidiary. If a parent holding company has filed this schedule pursuant to Rule 13d-1(c) or Rule 13d-1(d), attach an exhibit stating the identification of the relevant subsidiary. See Exhibit 99.1
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.

Bleichroeder LP

Signature:	Andrew Gundlach
Name/Title:	Andrew Gundlach, President and CEO
Date:	08/12/2025

Bleichroeder Holdings LLC

Signature:	Andrew Gundlach
Name/Title:	Andrew Gundlach, President and CEO
Date:	08/12/2025

Andrew Gundlach

Signature:	Andrew Gundlach
Name/Title:	Andrew Gundlach, Individual
Date:	08/12/2025

Exhibit Information

Exhibit 99.1 Subsidiary Information

FAQ

How many Aptose (APTO) shares does Bleichroeder report owning?

The filing reports 41,666 shares of Aptose common stock.

What percentage of Aptose does the 41,666 shares represent?

The 41,666 shares represent 1.61% of the common stock as stated in the filing.

Who filed the Schedule 13G/A for APTO?

The filing was made by Bleichroeder LP, Bleichroeder Holdings LLC and Andrew Gundlach.

Does the filer claim intent to influence control of Aptose?

No; the filing includes a certification that the securities were acquired and are held in the ordinary course of business and not to change or influence control.

When was the Schedule 13G/A signed?

Signatures in the filing are dated 08/12/2025.