MPM BioImpact Reports 5.62M Shares of Compass Therapeutics (CMPX)

Rhea-AI Filing Summary

MPM BioImpact LLC reports beneficial ownership of 5,622,505 shares of Compass Therapeutics common stock, equal to 4.1% of the class. The filing states the reporting person has sole voting power and sole dispositive power over the reported shares and identifies the filer as an investment adviser (IA). The filer certifies the securities are held in the ordinary course of business and not to change or influence control of the issuer. Because the stake is below 5%, this Schedule 13G/A reflects a passive, non-control disclosure under the Exchange Act.

Insights

Financial Analyst

TL;DR: MPM BioImpact reports a passive 4.1% stake (5.62M shares) in CMPX; this is informational and not a control move.

The filing discloses 5,622,505 shares owned representing 4.1% of Compass Therapeutics and confirms sole voting and dispositive power for those shares. Classification as an IA and the certification that holdings are in the ordinary course indicate a passive position consistent with Schedule 13G/A procedures. For investors, the disclosure documents institutional interest but does not signal a governance change given the sub-5% size and the stated non-control intent.

Corporate Governance Expert

TL;DR: The report documents a non-control institutional holding of 4.1% with sole voting/dispositive power; governance impact is minimal.

Itemized reporting shows no shared power and affirms the position is not intended to influence control. The use of Schedule 13G/A and the Item 10 certification are consistent with a passive, disclosure-driven filing rather than an activist or control-oriented approach. From a governance perspective, the filing does not trigger control disclosures or group formation and should not materially alter board or shareholder dynamics by itself.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 1)

Compass Therapeutics, Inc.

(Name of Issuer)

Common Stock, par value $0.001 per share

(Title of Class of Securities)

20454B104

(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. 20454B104

1

Names of Reporting Persons

MPM BioImpact 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 5,622,505.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 5,622,505.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

5,622,505.00

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)

4.1 %

12

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Compass Therapeutics, Inc.
(b)	Address of issuer's principal executive offices: 80 GUEST STREET, BOSTON, MA, 02135.
Item 2.
(a)	Name of person filing: MPM BioImpact LLC
(b)	Address or principal business office or, if none, residence: 399 Boylston Street, Suite 1100 Boston, MA 02116
(c)	Citizenship: Delaware
(d)	Title of class of securities: Common Stock, par value $0.001 per share
(e)	CUSIP No.: 20454B104
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: 5,622,505
(b)	Percent of class: 4.1%
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 5,622,505
	(ii) Shared power to vote or to direct the vote: 0
	(iii) Sole power to dispose or to direct the disposition of: 5,622,505
	(iv) Shared power to dispose or to direct the disposition of: 0
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.
	Not Applicable
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.

MPM BioImpact LLC

Signature:	/s/ Christopher Wolf
Name/Title:	Chief Financial Officer
Date:	08/12/2025

FAQ

How many Compass Therapeutics (CMPX) shares does MPM BioImpact LLC report owning?

The filing reports beneficial ownership of 5,622,505 shares.

What percentage of CMPX does the reported holding represent?

The reported shares represent 4.1% of the outstanding class.

Does MPM BioImpact claim voting or dispositive power over the shares?

Yes, the filing reports sole voting power and sole dispositive power for the 5,622,505 shares.

What type of filer is MPM BioImpact LLC identified as?

The reporting person is identified as an investment adviser (IA).

Does the filing indicate the stake is intended to change control of Compass Therapeutics?

No. The certification states the securities are held in the ordinary course of business and not to change or influence control of the issuer.

Is the reported ownership above the 5% reporting threshold?

No. The reported 4.1% stake is below the 5% threshold described in the filing.