Compass Therapeutics accounting chief buys 2,500 shares

The reported 400,000-share position includes 62,500 unvested restricted stock units subject to service-based vesting.

Rhea-AI Filing Summary

Neil Lerner, Compass Therapeutics, Inc.’s Chief Accounting Officer, reported a direct purchase of 2,500 common shares at $1.14 per share on September 24, 2026. His reported direct position after the purchase was 400,000 shares, including 62,500 unvested restricted stock units. No Rule 10b5-1 plan is reported.

Insider Trade Summary

Net Buyer: 2,500 shares

Net Buy 1 txn

Insider Lerner Neil

Role Chief Accounting Officer

Bought 2,500 shs ($3K)

Type	Security	Shares	Price	Value
Purchase	Common Stock F1	2,500	$1.14	$3K

Holdings After Transaction: Common Stock — 400,000 shares (Direct)

Footnotes (1)

1. F1. 62,500 of the shares represents unvested restricted stock units ("RSU") granted on January 2, 2026. Each RSU represents a contingent right to receive one share of common stock. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first installment vested on January 2, 2027.

Key Figures

Common shares purchased: 2,500 shares Purchase price: $1.14 per share Reported direct position after purchase: 400,000 shares +1 more

4 metrics

Common shares purchased 2,500 shares September 24, 2026

Purchase price $1.14 per share September 24, 2026

Reported direct position after purchase 400,000 shares After the September 24, 2026 purchase

Unvested restricted stock units 62,500 RSUs Granted January 2, 2026

Key Terms

restricted stock units, service-based vesting conditions, Rule 10b5-1 plan

3 terms

restricted stock units financial

"unvested restricted stock units"

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

service-based vesting conditions financial

"subject to service-based vesting conditions"

Rule 10b5-1 plan regulatory

"no Rule 10b5-1 plan is reported"

A Rule 10b5-1 plan is a prearranged, written schedule that lets corporate insiders buy or sell company stock at set times or amounts, even if they later learn material nonpublic information. Think of it like setting an automatic thermostat for trades: it creates a clear record that trades were planned in advance, reducing the risk of insider-trading accusations and helping investors trust that insider transactions are routine rather than based on secret information.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

How many CMPX shares did its chief accounting officer buy, and at what price?

Neil Lerner purchased 2,500 common shares at $1.14 per share on September 24, 2026.

What are the vesting terms for the CMPX chief accounting officer’s restricted stock units?

The 62,500 unvested restricted stock units were granted on January 2, 2026, are subject to service-based vesting conditions, and vest in four equal annual installments, with the first installment vesting on January 2, 2027.

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

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Available on EDGAR 09/25/2026 - 08:02 AM Accepted by SEC EDGAR 09/25/2026 - 08:01 AM Learn about SEC filing dates

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Lerner Neil

(Last) (First) (Middle)

C/O COMPASS THERAPEUTICS, INC.

80 GUEST STREET, SUITE 601

(Street)

BOSTON MASSACHUSETTS 02135

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Compass Therapeutics, Inc. [ CMPX ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Accounting Officer

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
09/24/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	09/24/2026		P		2,500	A	$1.14	400,000(1)	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. 62,500 of the shares represents unvested restricted stock units ("RSU") granted on January 2, 2026. Each RSU represents a contingent right to receive one share of common stock. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first installment vested on January 2, 2027.

	/s/ Neil Lerner	09/25/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)