Korro Bio (KRRO) counsel’s mandatory share sale covers RSU tax

Rhea-AI Filing Summary

Korro Bio, Inc. General Counsel Jeffrey Cerio reported an open-market sale of 6,609 shares of common stock at a weighted-average price of $10.83 per share. According to the filing, this was a mandatory sale solely to satisfy tax withholding obligations from vested restricted stock units under the 2023 equity plan.

After this transaction, Cerio holds 35,293 shares directly, including 20,951 shares underlying restricted stock units that are scheduled to vest on December 15, 2026, if his service with the company continues through that date.

Insider Trade Summary

Net Seller: 6,609 shares ($71,575)

Net Sell 1 txn

Insider Cerio Jeffrey

Role General Counsel

Sold 6,609 shs ($72K)

Type	Security	Shares	Price	Value
Sale	Common Stock	6,609	$10.83	$72K

Holdings After Transaction: Common Stock — 35,293 shares (Direct, null)

Footnotes (1)

1. Represents the mandatory sale of shares of common stock solely to satisfy tax withholding obligations incurred upon vesting and settlement of a restricted stock unit (RSU) granted under the Issuer's 2023 Stock Option and Incentive Plan (the 2023 Plan). The price reported in Column 4 is a weighted-average price. The shares were sold in multiple transactions at prices ranging from $10.58 to $11.35, inclusive. Full information regarding the number of shares sold at each separate price can be provided to the issuer, any security holder of the issuer or the staff of the Securities and Exchange Commission upon request. Includes 20,951 shares of common stock issuable upon settlement of a RSU granted under the 2023 Plan that will vest on December 15, 2026 subject to the reporting person maintaining a continuous Service Relationship (as defined in the 2023 Plan) through such date.

Key Figures

Shares sold: 6,609 shares Weighted-average sale price: $10.83 per share Post-transaction holdings: 35,293 shares +2 more

5 metrics

Shares sold 6,609 shares Open-market sale on 2026-06-16 to cover tax withholding

Weighted-average sale price $10.83 per share Common stock sale on 2026-06-16

Post-transaction holdings 35,293 shares Common stock held directly after sale

Unvested RSUs 20,951 shares RSUs scheduled to vest on December 15, 2026

Sale price range $10.58–$11.35 per share Price range of multiple sale transactions

Key Terms

restricted stock unit (RSU), weighted-average price, 2023 Stock Option and Incentive Plan, continuous Service Relationship

4 terms

restricted stock unit (RSU) financial

"Represents the mandatory sale of shares of common stock solely to satisfy tax withholding obligations incurred upon vesting and settlement of a restricted stock unit (RSU)..."

A restricted stock unit (RSU) is a promise from a company to give an employee company shares (or cash equal to their value) at a future date if certain conditions are met, such as staying with the company or hitting performance targets. For investors, RSUs matter because when they convert into actual shares they increase the number of shares available and can create selling pressure as employees cash out—think of them as a future paycheck paid in company stock.

weighted-average price financial

"The price reported in Column 4 is a weighted-average price. The shares were sold in multiple transactions..."

2023 Stock Option and Incentive Plan financial

"RSU granted under the Issuer's 2023 Stock Option and Incentive Plan (the 2023 Plan)."

continuous Service Relationship financial

"will vest on December 15, 2026 subject to the reporting person maintaining a continuous Service Relationship..."

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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^*

Cerio Jeffrey

(Last) (First) (Middle)

C/O KORRO BIO, INC.

60 FIRST STREET, 2ND FLOOR, SUITE 250

(Street)

CAMBRIDGE MASSACHUSETTS 02141

(City) (State) (Zip)

UNITED STATES

(Country)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
06/16/2026

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	06/16/2026		S(1)		6,609	D	$10.83(2)	35,293(3)	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 the mandatory sale of shares of common stock solely to satisfy tax withholding obligations incurred upon vesting and settlement of a restricted stock unit (RSU) granted under the Issuer's 2023 Stock Option and Incentive Plan (the 2023 Plan).

2. The price reported in Column 4 is a weighted-average price. The shares were sold in multiple transactions at prices ranging from $10.58 to $11.35, inclusive. Full information regarding the number of shares sold at each separate price can be provided to the issuer, any security holder of the issuer or the staff of the Securities and Exchange Commission upon request.

3. Includes 20,951 shares of common stock issuable upon settlement of a RSU granted under the 2023 Plan that will vest on December 15, 2026 subject to the reporting person maintaining a continuous Service Relationship (as defined in the 2023 Plan) through such date.

	/s/ Jeffrey Cerio	06/17/2026
	** 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 Korro Bio (KRRO) report for Jeffrey Cerio?

Korro Bio reported that General Counsel Jeffrey Cerio sold 6,609 shares of common stock at a weighted-average price of $10.83 per share. The sale was described as mandatory to cover tax withholding obligations from vesting restricted stock units under the company’s 2023 equity plan.

Was the Korro Bio (KRRO) insider sale a discretionary trade?

The sale was described as a mandatory transaction to satisfy tax withholding obligations arising from the vesting and settlement of restricted stock units. This characterization indicates it was driven by tax requirements rather than a discretionary decision to reduce equity exposure in Korro Bio shares.

How many Korro Bio (KRRO) shares does Jeffrey Cerio hold after the transaction?

Following the reported sale, General Counsel Jeffrey Cerio holds 35,293 Korro Bio common shares directly. This total includes 20,951 shares underlying restricted stock units that are scheduled to vest on December 15, 2026, contingent on his continued service relationship with the company.

What price range were the Korro Bio (KRRO) insider shares sold at?

The weighted-average sale price reported was $10.83 per share, with individual trades executed between $10.58 and $11.35. Detailed breakdowns of the number of shares sold at each separate price are available from the company, other shareholders, or SEC staff upon request.

What are the terms of Jeffrey Cerio’s unvested RSUs at Korro Bio (KRRO)?

Cerio’s holdings include 20,951 shares of common stock issuable upon settlement of restricted stock units granted under the 2023 Stock Option and Incentive Plan. These RSUs are scheduled to vest on December 15, 2026, provided he maintains a continuous service relationship through that date.