Korro Bio (KRRO) director-affiliated funds sell 2,143 shares under 10b5-1 plan

Q: Were the KRRO insider sales by Jean Francois Formela made under a 10b5-1 plan?

Yes. The filing states the shares were sold pursuant to a Rule 10b5-1 trading plan adopted by Jean Francois Formela on April 8, 2026 , indicating the sales were pre-arranged rather than discretionary at the time of execution.

Q: How many Korro Bio (KRRO) shares were sold by Atlas Venture Fund XI on August 11, 2026?

Atlas Venture Fund XI, L.P. sold 1,775 shares of Korro Bio common stock on August 11, 2026 . The reported $13.96 price is a weighted average, with individual trades between $13.95 and $14.00 per share.

Q: How many Korro Bio (KRRO) shares were sold by Atlas Venture Opportunity Fund II on August 11, 2026?

Atlas Venture Opportunity Fund II, L.P. sold 368 shares of Korro Bio common stock on August 11, 2026 . These sales also used a weighted average price of $13.96 , with execution prices ranging from $13.95 to $14.00 per share.

Q: Does Jean Francois Formela claim full beneficial ownership of the KRRO shares sold?

No. The filing explains the shares are held by Atlas venture funds and their general partners , and Jean Francois Formela disclaims Section 16 beneficial ownership of these shares except to the extent of any pecuniary interest.

Q: What price range did the Korro Bio (KRRO) insider sales occur at on August 11, 2026?

The sales occurred at prices ranging from $13.95 to $14.00 per share. The Form 4 reports a weighted average price of $13.96 per share, and notes that trade-level detail is available upon request.

Filing Impact

(Neutral)

Filing Sentiment

(Negative)

Form Type

Rhea-AI Filing Summary

Korro Bio, Inc. director Jean Francois Formela reported indirect sales of Korro Bio common stock on August 11, 2026. A total of 2,143 shares were sold at a weighted average price of $13.96 per share, in transactions executed under a Rule 10b5-1 trading plan adopted on April 8, 2026. The sold shares were held by Atlas Venture Fund XI, L.P. and Atlas Venture Opportunity Fund II, L.P., and Formela disclaims Section 16 beneficial ownership except to the extent of any pecuniary interest.

Insider Trade Summary 10b5-1

Net Seller: 2,143 shares

Net Sell 2 txns

Insider FORMELA JEAN FRANCOIS

Role Director

Sold 2,143 shs ($30K)

Type	Security	Shares	Price	Value
Sale	Common Stock ^{F1, F2, F3}	1,775	$13.96	$25K
Sale	Common Stock ^{F1, F2, F4}	368	$13.96	$5K

Holdings After Transaction: Common Stock — 145,937 shares (Indirect, See footnote)

Footnotes (4)

F1. Shares were sold pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on April 8, 2026.
F2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $13.95 to $14.00 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 sold each separate price within the range set forth in this footnote.
F3. These shares are held directly by Atlas Venture Fund XI, L.P. ("Atlas XI"). Atlas Venture Associates XI, L.P. ("AVA XI LP") is the general partner of Atlas XI. Atlas Venture Associates XI, LLC ("AVA XI LLC") is the general partner of AVA XI LP. The Reporting Person is a member of AVA XI LLC and disclaims Section 16 beneficial ownership of such shares, except to the extent of his pecuniary interest therein, if any.
F4. These shares are held directly by Atlas Venture Opportunity Fund II, L.P. ("AVOF II"). Atlas Venture Associates Opportunity II, L.P. ("AVAO II LP") is the general partner of AVOF II. Atlas Venture Associates Opportunity II, LLC ("AVAO II LLC") is the general partner of AVAO II LP. The Reporting Person is a member of AVAO II LLC and disclaims Section 16 beneficial ownership of such shares, except to the extent of his pecuniary interest therein, if any.

Key Figures

Shares sold by Atlas Venture Fund XI: 1,775 shares Shares sold by Atlas Venture Opportunity Fund II: 368 shares Total shares sold: 2,143 shares +3 more

6 metrics

Shares sold by Atlas Venture Fund XI 1,775 shares Common stock sold on August 11, 2026

Shares sold by Atlas Venture Opportunity Fund II 368 shares Common stock sold on August 11, 2026

Total shares sold 2,143 shares Aggregate of reported sales on August 11, 2026

Weighted average sale price $13.96 per share Weighted average for sales on August 11, 2026

Trade price range $13.95–$14.00 per share Price range of individual transactions on August 11, 2026

10b5-1 plan adoption date April 8, 2026 Date the Rule 10b5-1 trading plan was adopted

Key Terms

Rule 10b5-1 trading plan, weighted average price, Section 16 beneficial ownership

3 terms

Rule 10b5-1 trading plan regulatory

"Shares were sold pursuant to a Rule 10b5-1 trading plan adopted..."

A Rule 10b5-1 trading plan is a pre-arranged schedule that allows company insiders to buy or sell stock at specific times, even if they have inside information. It helps prevent accusations of unfair trading by making these transactions look planned and transparent, rather than sneaky or illegal.

weighted average price financial

"The price reported in Column 4 is a weighted average price."

Weighted average price is the average price of a security where each trade or component is counted according to its size, so bigger trades pull the average more than smaller ones. Think of it like calculating the average cost of a grocery haul where items you bought more of have greater influence on the final per-item cost. Investors use it to understand the true average price paid or received, judge execution quality, and compare trading performance against market movement.

Section 16 beneficial ownership regulatory

"disclaims Section 16 beneficial ownership of such shares, except..."

FAQ

What insider transactions did Korro Bio (KRRO) report on August 11, 2026?

Korro Bio reported that entities associated with director Jean Francois Formela sold 2,143 shares of common stock on August 11, 2026 at a weighted average price of $13.96 per share, in open market or private transactions.

Were the KRRO insider sales by Jean Francois Formela made under a 10b5-1 plan?

Yes. The filing states the shares were sold pursuant to a Rule 10b5-1 trading plan adopted by Jean Francois Formela on April 8, 2026, indicating the sales were pre-arranged rather than discretionary at the time of execution.

How many Korro Bio (KRRO) shares were sold by Atlas Venture Fund XI on August 11, 2026?

Atlas Venture Fund XI, L.P. sold 1,775 shares of Korro Bio common stock on August 11, 2026. The reported $13.96 price is a weighted average, with individual trades between $13.95 and $14.00 per share.

How many Korro Bio (KRRO) shares were sold by Atlas Venture Opportunity Fund II on August 11, 2026?

Atlas Venture Opportunity Fund II, L.P. sold 368 shares of Korro Bio common stock on August 11, 2026. These sales also used a weighted average price of $13.96, with execution prices ranging from $13.95 to $14.00 per share.

Does Jean Francois Formela claim full beneficial ownership of the KRRO shares sold?

No. The filing explains the shares are held by Atlas venture funds and their general partners, and Jean Francois Formela disclaims Section 16 beneficial ownership of these shares except to the extent of any pecuniary interest.

What price range did the Korro Bio (KRRO) insider sales occur at on August 11, 2026?

The sales occurred at prices ranging from $13.95 to $14.00 per share. The Form 4 reports a weighted average price of $13.96 per share, and notes that trade-level detail is available upon request.

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Form 4 Insider Transactions: What Each Field Means →

Available on EDGAR 08/13/2026 - 05:05 PM Accepted by SEC EDGAR 08/13/2026 - 05:04 PM

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^*

FORMELA JEAN FRANCOIS

(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)
08/11/2026

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)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock	08/11/2026		S⁽¹⁾		1,775	D	$13.96⁽²⁾	704,781	I	See footnote⁽³⁾
Common Stock	08/11/2026		S⁽¹⁾		368	D	$13.96⁽²⁾	145,937	I	See footnote⁽⁴⁾

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)
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)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)

Explanation of Responses:

1. Shares were sold pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on April 8, 2026.

2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $13.95 to $14.00 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 sold each separate price within the range set forth in this footnote.

3. These shares are held directly by Atlas Venture Fund XI, L.P. ("Atlas XI"). Atlas Venture Associates XI, L.P. ("AVA XI LP") is the general partner of Atlas XI. Atlas Venture Associates XI, LLC ("AVA XI LLC") is the general partner of AVA XI LP. The Reporting Person is a member of AVA XI LLC and disclaims Section 16 beneficial ownership of such shares, except to the extent of his pecuniary interest therein, if any.

4. These shares are held directly by Atlas Venture Opportunity Fund II, L.P. ("AVOF II"). Atlas Venture Associates Opportunity II, L.P. ("AVAO II LP") is the general partner of AVOF II. Atlas Venture Associates Opportunity II, LLC ("AVAO II LLC") is the general partner of AVAO II LP. The Reporting Person is a member of AVAO II LLC and disclaims Section 16 beneficial ownership of such shares, except to the extent of his pecuniary interest therein, if any.

	/s/ Ommer Chohan, Attorney-in-fact	08/13/2026
	** 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)

Source: View Original Filing on SEC EDGAR