Compass Therapeutics (NASDAQ: CMPX) CAO buys 15,000 shares

Rhea-AI Filing Summary

Compass Therapeutics, Inc. Chief Accounting Officer Neil Lerner reported an open-market purchase of common stock. On April 29, 2026, he bought 15,000 shares at $1.89 per share. Following this transaction, he directly holds 397,500 common shares.

His holdings include 62,500 unvested restricted stock units granted on January 2, 2026. Each RSU represents a contingent right to receive one share of common stock and vests in four equal annual installments starting January 2, 2027.

Insider Trade Summary

Net Buyer: 15,000 shares ($28,350)

Net Buy 1 txn

Insider Lerner Neil

Role Chief Accounting Officer

Bought 15,000 shs ($28K)

Type	Security	Shares	Price	Value
Purchase	Common Stock	15,000	$1.89	$28K

Holdings After Transaction: Common Stock — 397,500 shares (Direct, null)

Footnotes (1)

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Key Figures

Shares purchased: 15,000 shares Purchase price: $1.89 per share Total shares after transaction: 397,500 shares +1 more

4 metrics

Shares purchased 15,000 shares Open-market purchase on April 29, 2026

Purchase price $1.89 per share Price for CMPX common stock in this transaction

Total shares after transaction 397,500 shares Directly held CMPX common shares post-trade

Unvested RSUs 62,500 units RSUs granted January 2, 2026, vesting annually from 2027

Key Terms

restricted stock units, RSU, contingent right, service-based vesting conditions, +1 more

5 terms

restricted stock units financial

"62,500 of the shares represents unvested restricted stock units ("RSU") granted on January 2, 2026."

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.

RSU financial

"62,500 of the shares represents unvested restricted stock units ("RSU") granted on January 2, 2026."

Restricted stock units (RSUs) are a form of company shares given to employees as part of their compensation, usually with certain restrictions or conditions, such as remaining with the company for a set period. When these restrictions lift, employees receive actual shares that they can sell or hold. For investors, RSUs can impact a company's stock supply and reflect the company's commitment to attracting and retaining talent.

contingent right financial

"Each RSU represents a contingent right to receive one share of common stock."

service-based vesting conditions financial

"The award is subject to service-based vesting conditions and vests in four equal annual installments"

annual installments financial

"vests in four equal annual installments, with the first installment vested on January 2, 2027."

Form 4 Insider Transactions: What Each Field Means →

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)
04/29/2026

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)
04/29/2026

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	04/29/2026		P		15,000	A	$1.89	397,500(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.

Remarks:

Explanatory Note: This amendment is being filed to correct the transaction code reported in Table I of the original Form 4 filed on April 29, 2026. The transaction was inadvertently reported using transaction code A. The correct transaction code is P, which reflects that the transaction was an open market purchase. All other information in the original filing remains unchanged.

	/s/ Neil Lerner	04/30/2026
	** 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)

FAQ

What insider transaction did CMPX Chief Accounting Officer Neil Lerner report?

Neil Lerner reported buying 15,000 shares of Compass Therapeutics common stock in an open-market transaction at $1.89 per share. The filing shows this as a direct ownership purchase, increasing his total directly held stake in the company.

How many Compass Therapeutics (CMPX) shares does Neil Lerner own after this trade?

After the transaction, Neil Lerner directly holds 397,500 shares of Compass Therapeutics common stock. This total includes both already vested shares and 62,500 unvested restricted stock units that may convert into additional shares as vesting conditions are met.

At what price did Neil Lerner buy CMPX shares in the latest Form 4/A?

Neil Lerner purchased 15,000 Compass Therapeutics shares at $1.89 per share in an open-market trade. This disclosed price reflects what he paid for each share in that specific transaction reported in the amended Form 4 filing.

What restricted stock units (RSUs) does Neil Lerner hold in Compass Therapeutics (CMPX)?

Neil Lerner holds 62,500 unvested restricted stock units granted on January 2, 2026. Each RSU can settle into one share of CMPX common stock, subject to service-based vesting conditions over four annual installments beginning January 2, 2027.

How do Neil Lerner’s RSUs in CMPX vest over time?

The 62,500 RSUs granted to Neil Lerner vest in four equal annual installments. The first installment vested on January 2, 2027, with the remaining installments scheduled annually thereafter, assuming required service-based vesting conditions continue to be satisfied.