[Form 4] Prime Medicine, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Prime Medicine, Inc. (PRME) – Form 4 insider transaction

Director and 10% owner David R. Liu disclosed the purchase of 21,000 shares of Prime Medicine common stock on 23-Jun-2025. The trade was executed under a previously adopted Rule 10b5-1 plan dated 3-Mar-2025, indicating it was pre-scheduled rather than opportunistic.

The weighted-average purchase price was $2.162 per share, with individual trades occurring between $2.06 – $2.25. Following the transaction, Liu’s direct ownership increased to 20,219,945 shares, an incremental addition of roughly 0.10 % to his existing stake.

No derivative securities were reported, and no sales occurred. While the absolute dollar value of the purchase (~$45,400) is modest relative to Liu’s overall holding, insider buying—especially by a high-ownership director—can be interpreted as a vote of confidence in the company’s prospects at current price levels.

Positive

• Insider purchase by a 10 % owner/director signals confidence and strengthens ownership alignment.
• Transaction executed under a Rule 10b5-1 plan demonstrates governance best practice and transparency.

Negative

• Purchase size is immaterial (≈0.10 % increase in holding), limiting financial impact.

Insights

Financial Analyst

TL;DR: Minor insider buy; signal positive but immaterial to valuation.

The 21k-share purchase increases Liu’s stake to 20.22 m shares. At a $2.16 average, the outlay is negligible versus his existing position. Nevertheless, insider buying during a depressed price range typically supports sentiment and may ease market concerns regarding liquidity or near-term dilution. From a valuation perspective, the purchase does not alter earnings, cash flow, or strategic trajectory; therefore, impact on intrinsic value is minimal. Investors may view the filing as an incremental confidence indicator rather than a catalyst.

Corporate Governance Expert

TL;DR: Scheduled 10b5-1 buy shows compliance and alignment.

The transaction was executed under a disclosed 10b5-1 plan, reinforcing adherence to governance best practices and reducing the likelihood of material non-public information abuse. Liu’s status as both director and 10 % owner already aligns his interests with shareholders; the additional shares marginally deepen that alignment. Governance risk remains unchanged, but transparency is a mild positive.

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).

X

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^*

Liu David R.

(Last) (First) (Middle)

C/O PRIME MEDICINE, INC.

60 FIRST STREET

(Street)

CAMBRIDGE MA 02141

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Prime Medicine, Inc. [ PRME ]

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

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

3. Date of Earliest Transaction (Month/Day/Year)
06/23/2025

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

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

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

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	06/23/2025		P(1)		21,000	A	$2.162(2)	20,219,945	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. The reported transaction was effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on March 3, 2025.

2. The price reported in column 4 is a weighted-average price. These shares were purchased in multiple transactions at prices ranging from $2.06 to $2.25, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote.

Remarks:

	/s/ Ryan Brown, attorney-in-fact	06/23/2025
	** 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.

FAQ

How many PRME shares did David R. Liu buy on 23-Jun-2025?

He purchased 21,000 shares of Prime Medicine common stock.

What was the average purchase price of the insider buy?

The weighted-average price reported was $2.162 per share, within a $2.06–$2.25 range.

How many PRME shares does Liu own after the transaction?

His direct beneficial ownership rose to 20,219,945 shares following the purchase.

Was the transaction part of a 10b5-1 trading plan?

Yes. The filing states the trade was made under a Rule 10b5-1 plan adopted on 3-Mar-2025.

Did the Form 4 report any derivative security activity?

No. No derivative securities were acquired or disposed of in the reported period.

Is the purchase considered material to Prime Medicine’s valuation?

Given the small size relative to Liu's total holding and PRME's share count, it is not material to valuation.