Korro Bio (NASDAQ: KRRO) discloses 41,902-share RSU grant to its General Counsel

Rhea-AI Filing Summary

Korro Bio, Inc. reported an equity award to its General Counsel in an insider ownership filing. Officer Jeffrey Cerio acquired 41,902 shares of common stock at a price of $0.00, reflecting a grant tied to restricted stock units under the company’s 2023 Stock Option and Incentive Plan.

The filing explains that these shares are issuable upon settlement of a restricted stock unit (RSU) award that will vest in two equal installments: 50% on June 15, 2026 and 50% on December 15, 2026, if he maintains a continuous service relationship through each vesting date. After this grant, he is shown as beneficially owning 41,902 shares directly.

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

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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^*

Cerio Jeffrey

(Last) (First) (Middle)

C/O KORRO BIO, INC.

60 FIRST STREET, 2ND FLOOR, SUITE 250

(Street)

CAMBRIDGE MA 02141

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Korro Bio, Inc. [ KRRO ]

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

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

3. Date of Earliest Transaction (Month/Day/Year)
12/15/2025

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(1)	12/15/2025		A		41,902	A	$0.00	41,902	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. Represents shares of common stock issuable upon settlement of a restricted stock unit (RSU) granted under the Issuer's 2023 Stock Option and Incentive Plan (the 2023 Plan) that will vest as follows: 50% on June 15, 2026 and 50% on December 15, 2026, in each case subject to the reporting person maintaining a continuous Service Relationship (as defined in the 2023 Plan) through each such date.

	/s/ Jeffrey Cerio	12/16/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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FAQ

What insider transaction did Korro Bio (KRRO) disclose in this filing?

Korro Bio disclosed that its General Counsel, Jeffrey Cerio, acquired 41,902 shares of common stock at a price of $0.00 through an equity award.

Who is the reporting person in the Korro Bio (KRRO) insider filing and what is their role?

The reporting person is Jeffrey Cerio, who serves as an officer of Korro Bio with the title of General Counsel.

When did the reported Korro Bio (KRRO) equity transaction occur?

The earliest transaction date reported for the equity grant is December 15, 2025.

How many Korro Bio (KRRO) shares does the General Counsel beneficially own after this grant?

Following the reported transaction, the filing shows the General Counsel beneficially owning 41,902 shares of common stock directly.

How do the Korro Bio (KRRO) restricted stock units granted to the General Counsel vest?

The restricted stock units are scheduled to vest 50% on June 15, 2026 and 50% on December 15, 2026, conditioned on maintaining a continuous service relationship through each date.

Under which equity plan were the Korro Bio (KRRO) restricted stock units granted?

The RSU award was granted under Korro Bio’s 2023 Stock Option and Incentive Plan, referred to in the filing as the 2023 Plan.