Sec Form 4 Filing - Bermingham Nessan @ Korro Bio, Inc. - 2023-11-03

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

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, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL OMB Number: 3235-0287 Expires: November 30, 2011 Estimated average burden hours per response... 0.5

1. Name and Address of Reporting Person Bermingham Nessan 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) (Last) (First) (Middle) C/O KORRO BIO, INC., ONE KENDALL SQUARE, BUILDING 600-700 3. Date of Earliest Transaction (MM/DD/YY) 11/03/2023 (Street) CAMBRIDGE, MA02139 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 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 11/03/2023 A( 1 ) 35,114 ( 1 ) A 35,114 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 (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 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 (MM/DD/YY) 7. Title and Amount of Underlying Securities (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 of Derivative Security: 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) $ 11.68 ( 2 ) 11/03/2023 A( 2 ) 67,061 ( 2 ) ( 3 ) 08/13/2030 Common Stock 67,061 ( 2 ) ( 2 ) ( 4 ) 67,061 D Stock Option (Right to Buy) $ 20.94 ( 2 ) 11/03/2023 A( 2 ) 24,712 ( 2 ) ( 5 ) 02/08/2033 Common Stock 24,712 ( 2 ) ( 2 ) ( 6 ) 24,712 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Bermingham Nessan C/O KORRO BIO, INC. ONE KENDALL SQUARE, BUILDING 600-700 CAMBRIDGE, MA02139 X Signatures /s/ Shelby Walker, Attorney-in-fact 11/07/2023 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Received in exchange for 706,702 shares of common stock of Korro Bio Ops, Inc. (f/k/a Korro Bio, Inc., "Legacy Korro") pursuant to an Agreement and Plan of Merger dated as of July 14, 2023 (the "Merger Agreement") by and among Legacy Korro, the Issuer (f/k/a Frequency Therapeutics, Inc.) and Frequency Merger Sub, Inc., a wholly owned subsidiary of the Issuer ("Merger Sub"). Under the terms of the Merger Agreement, on November 3, 2023, Merger Sub merged with and into Legacy Korro (the "Merger"), with Legacy Korro surviving the Merger as a wholly owned subsidiary of the Issuer. Upon the closing of the Merger, each share of Legacy Korro common stock was converted into the right to receive 0.049688 of a share of the Issuer's common stock, after giving effect to a reverse stock split of the Issuer's common stock of 1-for-50. Subsequent to the Merger, the name of the Issuer was changed from Frequency Therapeutics, Inc. to Korro Bio, Inc. ( 2 )Upon the closing of the Merger, each outstanding option to purchase shares of Legacy Korro common stock issued under the Korro Bio, Inc. 2019 Stock Incentive Plan (the "2019 Plan") was assumed by the Issuer and converted into an option to purchase the Issuer's common stock, on the same terms and conditions as were applicable under the 2019 Plan prior to the Merger, as adjusted for the exchange ratio and the reverse stock split. ( 3 )The shares subject to the option are fully vested and immediately exercisable. ( 4 )Received in exchange for a stock option to acquire 1,349,645 shares of Legacy Korro common stock issued under the 2019 Plan pursuant to the Merger Agreement. ( 5 )The shares subject to the option vest in 48 equal monthly installments commencing from August 14, 2022, subject to the Reporting Person's continued service on each such vesting date. ( 6 )Received in exchange for a stock option to acquire 497,347 shares of Legacy Korro common stock issued under the 2019 Plan pursuant to the Merger Agreement.

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.