Atlas Venture fund to sell 51 Korro Bio shares

Korro Bio, Inc. (KRRO) is the issuer for a notice by Atlas Venture Opportunity Fund II, L.P. to sell common stock under Rule 144.

Rhea-AI Filing Summary

Korro Bio, Inc. (KRRO) is the issuer for a notice by Atlas Venture Opportunity Fund II, L.P. to sell common stock under Rule 144. The filing indicates a proposed sale of 51 shares of Korro Bio common stock through Merrill Lynch with an aggregate market value of $700.23, at a time when 14,725,646 shares of common stock were outstanding. The filing also lists multiple recent secondary-market sales of Korro Bio common stock by Atlas Venture Fund XI, L.P. and Atlas Venture Opportunity Fund II, L.P., including a block of 101,579 shares sold on June 23, 2026 for $1,447,785.17.

Key Figures

Shares to be sold: 51 shares of common stock Aggregate market value of shares to be sold: $700.23 Shares outstanding: 14,725,646 shares +3 more

6 metrics

Shares to be sold 51 shares of common stock Number of Korro Bio shares covered by the Form 144 notice

Aggregate market value of shares to be sold $700.23 Aggregate market value for the 51 shares in the Form 144

Shares outstanding 14,725,646 shares Korro Bio common stock shares outstanding referenced in the Form 144

Largest single recent sale 101,579 shares for $1,447,785.17 Sale by Atlas Venture Fund XI, L.P. on 06/23/2026

Acquisition date of securities 04/22/2024 Date Atlas Venture Opportunity Fund II, L.P. acquired the shares in a Private Placement

Approximate date of sale 08/26/2026 Approximate sale date provided in the Form 144 securities information

Key Terms

Rule 144, Form 144, Private Placement

3 terms

Rule 144 regulatory

"See the definition of "person" in paragraph (a) of Rule 144."

Rule 144 is a U.S. securities regulation that sets conditions under which restricted or insider-held shares can be legally resold to the public, such as required holding periods, availability of public information, limits on how much can be sold at once, and certain filing requirements. For investors it matters because it determines when previously locked-up shares can enter the market — like a release valve that can increase supply, affect share price, and signal insider intent.

Form 144 regulatory

"144: Filer Information ... 144: Issuer Information"

Form 144 is a document that investors must file with the government when they plan to sell a large number of shares of a company's stock. It helps ensure transparency so everyone knows how many shares are being sold and when, which can impact the stock's price.

Private Placement financial

"Common Stock | 04/22/2024 | Private Placement | Issuer"

A private placement is a sale of securities directly to a selected group of investors, typically institutions or accredited investors, instead of through a public offering. It lets a company raise money faster and with fewer regulatory steps; for existing shareholders it matters because the newly issued shares, often sold at a discount, increase the share count and can dilute their ownership.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What does the Form 144 filing involving KRRO disclose?

It discloses that Atlas Venture Opportunity Fund II, L.P. has filed a notice of proposed sale under Rule 144 for 51 shares of Korro Bio, Inc. common stock, with an aggregate market value of $700.23, to be sold through Merrill Lynch.

How many KRRO shares are proposed to be sold under this Form 144?

The notice covers a proposed sale of 51 shares of Korro Bio, Inc. common stock, with an indicated aggregate market value of $700.23.

How many Korro Bio (KRRO) shares were outstanding according to this filing?

The filing states that 14,725,646 shares of Korro Bio, Inc. common stock were outstanding at the time referenced in the Form 144 securities information section.

Which holder is selling KRRO shares in this Form 144?

The Form 144 is filed for the account of Atlas Venture Opportunity Fund II, L.P., relating to proposed sales of Korro Bio, Inc. common stock under Rule 144.

What recent KRRO share sales by related funds are disclosed?

The filing lists several sales by Atlas Venture Fund XI, L.P. and Atlas Venture Opportunity Fund II, L.P., including a sale of 101,579 shares on June 23, 2026 for $1,447,785.17 and other transactions in May, June, July, and August 2026.

How were the KRRO shares originally acquired by the selling holder?

The Form 144 indicates that the Korro Bio, Inc. common stock to be sold by Atlas Venture Opportunity Fund II, L.P. was acquired on April 22, 2024 in a Private Placement from the issuer for cash.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 08/26/2026 - 05:25 PM EDT Accepted by SEC EDGAR 08/26/2026 - 05:23 PM EDT Learn about SEC filing dates

Form 144 Filer Information	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 144 NOTICE OF PROPOSED SALE OF SECURITIES PURSUANT TO RULE 144 UNDER THE SECURITIES ACT OF 1933
FORM 144

144: Filer Information

Filer CIK	0001885327
Filer CCC	XXXXXXXX
Is this a LIVE or TEST Filing?	LIVE TEST
Submission Contact Information
Name
Phone
E-Mail Address

144: Issuer Information

Name of Issuer	Korro Bio, Inc.
SEC File Number	001-39062
Address of Issuer	60 First Street 2nd Floor, Suite 250 Cambridge MASSACHUSETTS 02141
Phone	6174681999
Name of Person for Whose Account the Securities are To Be Sold	Atlas Venture Opportunity Fund II, L.P.
See the definition of "person" in paragraph (a) of Rule 144. Information is to be given not only as to the person for whose account the securities are to be sold but also as to all other persons included in that definition. In addition, information shall be given as to sales by all persons whose sales are required by paragraph (e) of Rule 144 to be aggregated with sales for the account of the person filing this notice.
Relationship to Issuer	Shareholder

144: Securities Information

Title of the Class of Securities To Be Sold	Name and Address of the Broker	Number of Shares or Other Units To Be Sold	Aggregate Market Value	Number of Shares or Other Units Outstanding	Approximate Date of Sale	Name the Securities Exchange
Common Stock	Merrill Lynch 555 California Street 18th Floor San Francisco CA 94104	51	700.23	14725646	08/26/2026	Nasdaq

Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144: Securities To Be Sold

Title of the Class	Date you Acquired	Nature of Acquisition Transaction	Name of Person from Whom Acquired	Is this a Gift?	Date Donor Acquired	Amount of Securities Acquired	Date of Payment	Nature of Payment *
Common Stock	04/22/2024	Private Placement	Issuer			51	04/22/2024	Cash

* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.

Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144: Securities Sold During The Past 3 Months

Name and Address of Seller	Title of Securities Sold	Date of Sale	Amount of Securities Sold	Gross Proceeds
Atlas Venture Fund XI, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	05/28/2026	2441	34051.95
Atlas Venture Fund XI, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	06/22/2026	3382	47178.9
Atlas Venture Fund XI, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	06/23/2026	101579	1447785.17
Atlas Venture Fund XI, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	06/24/2026	41345	603694.88
Atlas Venture Fund XI, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	07/02/2026	85955	1206249.49
Atlas Venture Fund XI, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	07/06/2026	817	11405.24
Atlas Venture Fund XI, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	08/11/2026	1775	24772.79
Atlas Venture Fund XI, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common	08/19/2026	23584	330159.49
Atlas Venture Opportunity Fund II, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	05/28/2026	419	5845.05
Atlas Venture Opportunity Fund II, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	06/22/2026	580	8091
Atlas Venture Opportunity Fund II, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	06/23/2026	17426	248369.29
Atlas Venture Opportunity Fund II, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	06/24/2026	7093	103567.73
Atlas Venture Opportunity Fund II, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	07/02/2026	14745	206923.96
Atlas Venture Opportunity Fund II, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	07/06/2026	8506	118742.91
Atlas Venture Opportunity Fund II, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	08/11/2026	368	5135.99
Atlas Venture Opportunity Fund II, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	08/19/2026	4884	68372.58

144: Remarks and Signature

Remarks
Date of Notice	08/26/2026
Date of Plan Adoption or Giving of Instruction, If Relying on Rule 10b5-1	04/08/2026
ATTENTION:
The person for whose account the securities to which this notice relates are to be sold hereby represents by signing this notice that he does not know any material adverse information in regard to the current and prospective operations of the Issuer of the securities to be sold which has not been publicly disclosed. If such person has adopted a written trading plan or given trading instructions to satisfy Rule 10b5-1 under the Exchange Act, by signing the form and indicating the date that the plan was adopted or the instruction given, that person makes such representation as of the plan adoption or instruction date.
Signature	Ommer Chohan
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)