Korro Bio (KRRO) director awarded 14,677 stock options at $10.59 strike price

Rhea-AI Filing Summary

Korro Bio director Katharine Knobil received a grant of stock options covering 14,677 shares of common stock at an exercise price of $10.59 per share. These options vest in full on the earlier of one year from the grant date or the next annual stockholder meeting, subject to her continued service as a non-employee director, and will expire on June 9, 2036.

Insights

Equity compensation analyst

Routine director stock option grant with standard vesting terms.

Director Katharine Knobil was awarded options on 14,677 shares of Korro Bio common stock at an exercise price of $10.59 per share. The Form 4 labels this as a grant or award, not an open-market purchase.

The options vest fully on the earlier of the one-year anniversary of the grant or the next annual stockholder meeting, conditioned on continued service as a non-employee director. The options expire on June 9, 2036, giving a long-dated incentive aligned with board tenure.

This appears to be standard equity compensation for board service rather than a discretionary market bet. With 14,677 derivative shares reported following the transaction and no sales, the filing mainly documents compensation structure, not a change in ownership sentiment.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider Knobil Katharine

Role null

Type	Security	Shares	Price	Value
Grant/Award	Stock Option (Right to Buy)	14,677	$0.00	--

Holdings After Transaction: Stock Option (Right to Buy) — 14,677 shares (Direct, null)

Footnotes (1)

1. [object Object]

Key Figures

Option grant size: 14,677 shares Exercise price: $10.59/share Shares after transaction: 14,677 derivative shares +1 more

4 metrics

Option grant size 14,677 shares Stock option award to director on grant date

Exercise price $10.59/share Strike price for the stock options

Shares after transaction 14,677 derivative shares Total stock options reported following grant

Option expiration June 9, 2036 Expiration date of the stock options

Key Terms

Stock Option (Right to Buy), exercise price, vesting, non-employee director, +1 more

5 terms

Stock Option (Right to Buy) financial

"security_title: Stock Option (Right to Buy)"

exercise price financial

"conversion_or_exercise_price: 10.5900"

The exercise price is the fixed amount at which you can buy or sell an asset, like a stock, when using an options contract. It matters because it helps determine whether exercising the option will be profitable or not, depending on the current market price. Think of it as the set price you agree on today to buy or sell later.

vesting financial

"The shares subject to the option vest in full on the earlier of (i) the one-year anniversary"

Vesting is the process by which you earn full ownership of something, like company stock or a retirement benefit, over time. It’s like earning the right to keep a gift piece by piece the longer you stay with a company, making sure employees stay committed before they receive all the benefits.

non-employee director financial

"subject to continued service as a non-employee director through the applicable vesting date"

annual meeting of stockholders financial

"or (ii) the date of the next annual meeting of stockholders"

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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^*

Knobil Katharine

(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)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
06/10/2026

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

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
Stock Option (Right to Buy)	$10.59	06/10/2026		A		14,677		(1)	06/09/2036	Common Stock	14,677	$0	14,677	D

Explanation of Responses:

1. The shares subject to the option vest in full on the earlier of (i) the one-year anniversary of the grant date or (ii) the date of the next annual meeting of stockholders, subject to continued service as a non-employee director through the applicable vesting date.

	/s/ Jeffrey Cerio, attorney-in-fact	06/11/2026
	** 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 did Katharine Knobil report in Korro Bio (KRRO) Form 4?

Katharine Knobil reported receiving a stock option grant for 14,677 shares of Korro Bio common stock. The options have an exercise price of $10.59 per share and represent routine equity compensation for her service as a non-employee director.

Is the Korro Bio (KRRO) Form 4 a stock purchase or compensation grant?

The Form 4 reflects a compensation grant, not an open-market stock purchase. It shows a stock option award coded as a grant or award acquisition, with zero price paid and an exercise price of $10.59 per underlying share of common stock.

What are the vesting terms of Katharine Knobil’s Korro Bio options?

The 14,677-share stock option vests in full on the earlier of one year from the grant date or the next annual stockholder meeting. Vesting is contingent on her continued service as a non-employee director through the applicable vesting date.

When do Katharine Knobil’s Korro Bio (KRRO) stock options expire?

The reported stock options expire on June 9, 2036. This long-term expiration date provides an extended window in which she can choose to exercise the options at the fixed $10.59 per-share exercise price for Korro Bio common stock.

How many Korro Bio shares are covered by Katharine Knobil’s new options?

The grant covers options on 14,677 shares of Korro Bio common stock. Following this transaction, the Form 4 shows 14,677 derivative shares attributable to this award, with no indication of sales or exercises associated with the grant date.

Does the Korro Bio Form 4 indicate any stock sales by Katharine Knobil?

The Form 4 does not report any stock sales by Katharine Knobil. It only shows an acquisition of derivative securities through a stock option grant, with no corresponding disposal transactions or open-market trades disclosed in this filing.