Korro Bio holder plans 1,750-share stock sale

Korro Bio, Inc. (KRRO) is the issuer for which Atlas Venture Opportunity Fund II, L.P. has filed a Notice of Proposed Sale of Securities under Rule 144 covering 1,750 shares of common stock.

Rhea-AI Filing Summary

Korro Bio, Inc. (KRRO) is the issuer for which Atlas Venture Opportunity Fund II, L.P. has filed a Notice of Proposed Sale of Securities under Rule 144 covering 1,750 shares of common stock. The notice also lists multiple recent open‑market sales of Korro Bio common stock by affiliated Atlas funds.

Key Figures

Securities to be sold: 1,750 shares of common stock Single-day sale volume: 101,579 shares of common stock Proceeds from June 23, 2026 sale: $1,447,785.17 +3 more

6 metrics

Securities to be sold 1,750 shares of common stock Planned Rule 144 sale by Atlas Venture Opportunity Fund II, L.P.

Single-day sale volume 101,579 shares of common stock Sold on June 23, 2026 by Atlas Venture Fund XI, L.P.

Proceeds from June 23, 2026 sale $1,447,785.17 Gross proceeds for 101,579 Korro Bio shares sold by Atlas Venture Fund XI, L.P.

Another large sale volume 85,955 shares of common stock Sold on July 2, 2026 by Atlas Venture Fund XI, L.P.

Proceeds from July 2, 2026 sale $1,206,249.49 Gross proceeds for 85,955 Korro Bio shares sold by Atlas Venture Fund XI, L.P.

Proceeds from June 23, 2026 Opportunity Fund sale $248,369.29 Gross proceeds for 17,426 shares sold by Atlas Venture Opportunity Fund II, L.P.

Key Terms

Rule 144, Private Placement, Nasdaq, Common Stock

4 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.

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.

Nasdaq market

"Common Stock ... 09/11/2026 | Nasdaq"

The Nasdaq is a stock exchange where many companies' shares are bought and sold, functioning much like a marketplace for investments. It matters to investors because it provides a platform to buy and sell ownership stakes in companies, helping them track the value of those companies and make informed decisions. As one of the largest and most technology-focused markets, it also reflects trends and developments in the business world.

Common Stock financial

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

Common stock represents ownership shares in a company, giving investors a stake in its success and a say in important decisions through voting rights. It is the most common type of stock traded on markets and can provide income through dividends, as well as potential for value growth. For investors, holding common stock means sharing in the company’s profits and risks.

FAQ

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

What does Korro Bio (KRRO) disclose in this Form 144 filing?

The filing reports that Atlas Venture Opportunity Fund II, L.P. intends to sell 1,750 shares of Korro Bio common stock under Rule 144 and provides details of multiple recent sales of Korro Bio shares by related Atlas funds.

How many Korro Bio (KRRO) shares are covered by the proposed Rule 144 sale?

The proposed Rule 144 sale covers 1,750 shares of Korro Bio common stock for the account of Atlas Venture Opportunity Fund II, L.P., as stated in the securities information and securities-to-be-sold sections.

Who is the selling security holder in this Korro Bio (KRRO) Form 144?

The selling security holder for the proposed sale is Atlas Venture Opportunity Fund II, L.P.. The filing also lists past three‑month sales of Korro Bio common stock by Atlas Venture Fund XI, L.P. and Atlas Venture Opportunity Fund II, L.P.

What recent Korro Bio (KRRO) share sales by Atlas funds are disclosed?

The document lists several sales, including a sale on June 23, 2026 by Atlas Venture Fund XI, L.P. of 101,579 shares of Korro Bio common stock for $1,447,785.17, along with other transactions in June, July and August 2026.

How were the Korro Bio (KRRO) shares to be sold originally acquired?

The 1,750 Korro Bio common shares covered by the proposed sale were acquired on April 22, 2024 in a Private Placement from the issuer for cash, as indicated in the securities-to-be-sold section.

On which market is Korro Bio (KRRO) stock referenced in this filing traded?

The securities information section identifies Korro Bio’s common stock as traded on Nasdaq, in connection with the planned Rule 144 sale by Atlas Venture Opportunity Fund II, L.P.

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

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Available on EDGAR 09/11/2026 - 05:10 PM EDT Accepted by SEC EDGAR 09/11/2026 - 05:09 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	1750	22855	14725646	09/11/2026	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			1750	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	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 Fund XI, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	08/26/2026	249	3476.86
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
Atlas Venture Opportunity Fund II, L.P. 300 Technology Sq Ste 8 Cambridge MA 02139	Common Stock	08/26/2026	51	712.13

144: Remarks and Signature

Remarks
Date of Notice	09/11/2026
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)