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Korro Bio (KRRO) director-tied funds sell 28K shares on Aug. 19

Filing Impact
(Moderate)
Filing Sentiment
(Negative)
Form Type
4

Rhea-AI Filing Summary

Korro Bio, Inc. (KRRO) director Jean Francois Formela reported indirect open-market sales of Korro Bio common stock by venture funds with which he is associated. On August 19, 2026, Atlas Venture Fund XI, L.P. sold 23,584 shares and Atlas Venture Opportunity Fund II, L.P. sold 4,884 shares, totaling 28,468 shares at a weighted average price of $14.00 per share, under a Rule 10b5-1 trading plan. The shares are held by the Atlas funds; Formela disclaims Section 16 beneficial ownership except to the extent of any pecuniary interest.

Positive

  • None.

Negative

  • None.
Insider FORMELA JEAN FRANCOIS
Role Director
Sold 28,468 shs ($399K)
Type Security Shares Price Value
Sale Common Stock F1, F2, F3 23,584 $14.00 $330K
Sale Common Stock F1, F2, F4 4,884 $14.00 $68K
Holdings After Transaction: Common Stock — 141,053 shares (Indirect, See footnote)
Footnotes (4)
  1. F1. Shares were sold pursuant to a Rule 10b5-1 trading plan on April 8, 2026.
  2. 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 $14.15 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. 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.
  4. 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.
Shares sold by Atlas Venture Fund XI, L.P. 23,584 shares Common Stock sale on August 19, 2026
Shares sold by Atlas Venture Opportunity Fund II, L.P. 4,884 shares Common Stock sale on August 19, 2026
Total shares sold 28,468 shares Aggregate net-sell shares across reported transactions
Weighted average sale price $14.00 per share Multiple transactions at prices from $13.95 to $14.15
Rule 10b5-1 trading plan regulatory
"Shares were sold pursuant to a Rule 10b5-1 trading plan on April 8, 2026."
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 to the extent"
indirect ownership financial
"The transactions are reported as indirect ownership."

FAQ

What insider transaction did Korro Bio (KRRO) disclose in this Form 4?
Korro Bio (KRRO) disclosed that director Jean Francois Formela reported indirect sales of 28,468 shares of common stock on August 19, 2026, executed by Atlas venture funds with which he is associated.

How many Korro Bio (KRRO) shares were sold and at what price?
A total of 28,468 shares of Korro Bio common stock were sold at a weighted average price of $14.00 per share, with individual trade prices ranging from $13.95 to $14.15.

Who actually held the Korro Bio (KRRO) shares that were sold?
The sold shares were held by Atlas Venture Fund XI, L.P. and Atlas Venture Opportunity Fund II, L.P.. Jean Francois Formela is a member of the general partner entities and disclaims Section 16 beneficial ownership except for any pecuniary interest.

Were the Korro Bio (KRRO) share sales made under a Rule 10b5-1 plan?
Yes. The filing states the shares were sold pursuant to a Rule 10b5-1 trading plan that was entered into on April 8, 2026, and the document-level 10b5-1 checkbox is affirmed.

Is this Korro Bio (KRRO) Form 4 reporting direct or indirect ownership?
The transactions are reported as indirect ownership. The shares are held by Atlas venture funds, and the reporting person notes indirect interests through the funds’ general partners, with a disclaimer of beneficial ownership except for any pecuniary interest.

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Form 4 Insider Transactions: What Each Field Means →
SEC Form 4
FORM 4UNITED 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*
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)
XDirector10% Owner
Officer (give title below)Other (specify below)
2a. Foreign Trading Symbol
3. Date of Earliest Transaction (Month/Day/Year)
08/19/2026		6. Individual or Joint/Group Filing (Check Applicable Line)
XForm 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)
CodeVAmount(A) or (D)Price
Common Stock08/19/2026S(1)23,584D$14(2)681,197ISee footnote(3)
Common Stock08/19/2026S(1)4,884D$14(2)141,053ISee 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)
CodeV(A)(D)Date ExercisableExpiration DateTitleAmount or Number of Shares
Explanation of Responses:
1. Shares were sold pursuant to a Rule 10b5-1 trading plan 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 $14.15 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-fact08/21/2026
** Signature of Reporting PersonDate
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