Welcome to our dedicated page for Korro Bio SEC filings (Ticker: KRRO), a comprehensive resource for investors and traders seeking official regulatory documents including 10-K annual reports, 10-Q quarterly earnings, 8-K material events, and insider trading forms.
Korro Bio, Inc. filings document the regulatory record of a biopharmaceutical company developing RNA-editing genetic medicines through its OPERA® platform. Its 8-K reports disclose operating and financial results, corporate presentations, clinical and regulatory program updates, capital-structure activity, and material events tied to its RNA-editing pipeline.
The company’s filings also cover proxy governance, executive compensation, equity incentive and inducement arrangements, employment agreements, and material collaboration and license agreements. Program-related disclosures focus on KRRO-121, hyperammonemia in urea cycle disorders and hepatic encephalopathy, GalNAc-conjugated oligonucleotide research, alpha-1 antitrypsin deficiency, risk factors, and the financing and governance framework supporting Korro Bio’s development-stage operations.
Korro Bio, Inc. reports that President and CEO Ram Aiyar sold 5,802 shares of common stock on August 4, 2026 at a weighted-average price of $10.844 per share in mandatory sales solely to cover tax withholding on vested RSUs under its 2023 Stock Option and Incentive Plan. Following these transactions, he holds 69,046 shares directly, including 20,000 unvested RSUs scheduled to vest on February 1, 2027 subject to a continuous Service Relationship, and 4,613 shares are held indirectly through The Ram Aiyar Irrevocable Trust.
Atlas Venture funds filed Amendment No. 1 to Schedule 13D reporting their combined ownership in Korro Bio, Inc. common stock. Collectively, the reporting entities beneficially own 852,861 shares of common stock, representing an estimated 5.9% of Korro Bio’s outstanding shares.
Atlas Venture Fund XI, L.P. and its related general partners report 706,556 shares, or 4.9% of the outstanding common stock, with shared voting and dispositive power. Atlas Venture Opportunity Fund II, L.P. and its related general partners report 146,305 shares, or 1.0%. Percentages are based on 14,422,571 shares outstanding as of May 4, 2026. The funds are under common control and state they may be deemed a group, but they expressly disclaim group membership. Recent transactions within the past sixty days are listed in an exhibit.
KRRO shareholder Ram Aiyar filed a notice of proposed sale of 5,802 common shares through Fidelity Brokerage Services LLC, with an aggregate market value of $662,917.47, expected around August 4, 2026 on NASDAQ. The shares are scheduled to come from restricted stock vesting granted as compensation by the issuer on August 3, 2026. KRRO reports 14,422,571 common shares outstanding. In the prior three months, Aiyar sold 15,152 common shares on May 29, 2026 for gross proceeds of $196,675.99.
BlackRock, Inc. reports beneficial ownership of common stock of Korro Bio, Inc. as an institutional holder. BlackRock reports beneficial ownership of 747,546 shares of Korro Bio common stock, representing 5.2% of the class. It has sole voting power over 738,098 shares and sole dispositive power over 747,546 shares, with no shared voting or dispositive power reported. Various underlying clients or accounts have economic rights to dividends or sale proceeds, but no single person has more than five percent of Korro Bio’s outstanding common shares.
Vincent Loic A reported acquisition or exercise transactions in this Form 4 filing.
Korro Bio, Inc. Chief Scientific Officer Vincent Loic A received an equity award covering 7,500 shares of common stock, issuable upon settlement of restricted stock units (RSUs) granted under the 2023 Stock Option and Incentive Plan. These RSUs vest 50% on July 15, 2027 and 50% on July 15, 2028, subject to maintaining a continuous Service Relationship. Following this grant, he reports direct ownership of 25,797 shares, including 18,358 unvested RSU-based shares scheduled to vest 10,858 on December 15, 2026, 3,750 on July 15, 2027, and 3,750 on July 15, 2028.
Dolan Oliver reported acquisition or exercise transactions in this Form 4 filing.
Oliver Dolan, Senior Vice President, Finance of Korro Bio, Inc., received a grant of 5,500 shares of common stock issuable upon settlement of restricted stock units on July 15, 2026. These RSUs vest 50% on July 15, 2027 and 50% on July 15, 2028, subject to a continuous Service Relationship. Following this award, he directly holds 23,599 shares, including 16,241 unvested RSU shares scheduled to vest between December 15, 2026 and July 15, 2028.
Cerio Jeffrey reported acquisition or exercise transactions in this Form 4 filing.
Korro Bio, Inc. reported that General Counsel Jeffrey Cerio received a grant of 6,500 shares of common stock in the form of restricted stock units (RSUs) under the 2023 Stock Option and Incentive Plan on July 15, 2026, at a stated price of $0.0000 per share. These RSUs will vest 50% on July 15, 2027 and 50% on July 15, 2028, subject to maintaining a continuous Service Relationship. Following this award, Cerio holds 41,793 shares directly, including 27,451 unvested RSUs scheduled to vest in tranches on December 15, 2026 and July 15 of 2027 and 2028.
Chappell Todd reported acquisition or exercise transactions in this Form 4 filing.
Korro Bio, Inc. reported that Chief Operating Officer Todd Chappell received a grant of restricted stock units representing 7,500 shares of common stock under its 2023 Stock Option and Incentive Plan. These RSUs vest 50% on July 15, 2027 and 50% on July 15, 2028, subject to a continuous Service Relationship.
After this award, Chappell beneficially owns 24,464 shares of common stock, including 17,566 shares underlying unvested RSUs scheduled to vest in 2026, 2027 and 2028.
Korro Bio director-linked funds reported open-market sales of 110,023 shares of Common Stock. The transactions were executed on July 2 and July 6, 2026 at weighted average prices around $14 per share, through entities associated with Atlas Venture funds.
The sales were made pursuant to a Rule 10b5-1 trading plan adopted on April 8, 2026, indicating they were pre-scheduled rather than discretionary market-timed trades. Following these transactions, the reporting entities together continue to hold large indirect positions, including 146,305 and 706,556 shares of Korro Bio common stock.
The filing by an issuer shows proposed and recent resale activity in Common Stock related to a Private Placement dated 03/23/2023. The Form 144 lists multiple sales by Atlas Venture affiliates during May–July 2026, including large dispositions on 06/23/2026 and 07/02/2026.
Examples include Atlas Venture Fund XI, L.P.: 101,579 shares sold on 06/23/2026 for $1,447,785.17, and Atlas Venture Opportunity Fund II, L.P.: 17,426 shares sold on 06/23/2026 for $248,369.29.