Korro Bio, Inc. Form 4 Filings

Korro Bio, Inc. (KRRO) director Jean Francois Formela, through investment funds associated with Atlas Venture, reported indirect sales of a total of 300 shares of common stock on August 26, 2026. The shares were sold pursuant to a Rule 10b5-1 trading plan at a weighted average price of about $13.96 per share, in multiple trades between $13.955 and $13.98. The shares are held by Atlas Venture Fund XI, L.P. and Atlas Venture Opportunity Fund II, L.P., and Formela disclaims Section 16 beneficial ownership except to the extent of his pecuniary interest.

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.

Korro Bio, Inc. director Jean Francois Formela reported indirect sales of Korro Bio common stock on August 11, 2026. A total of 2,143 shares were sold at a weighted average price of $13.96 per share, in transactions executed under a Rule 10b5-1 trading plan adopted on April 8, 2026. The sold shares were held by Atlas Venture Fund XI, L.P. and Atlas Venture Opportunity Fund II, L.P., and Formela disclaims Section 16 beneficial ownership except to the extent of any pecuniary interest.

Korro Bio, Inc. reported insider purchases of common stock by entities associated with Lynx1 Capital Management LP and Weston Nichols. On August 6, 2026, Lynx1 Master Fund LP purchased 5,222 shares at a weighted average price of $11.3998 per share, and on August 10, 2026 it purchased 1,462 shares at a weighted average price of $13.1869, for a total of 6,684 shares, all held indirectly. The investment manager and Mr. Nichols disclaim beneficial ownership except to the extent of any pecuniary interest.

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.

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.

Korro Bio director Jean Francois Formela, reporting indirect interests in Atlas Venture funds, disclosed sales of 171,405 shares of common stock from June 22–24, 2026 at weighted-average prices between $13.95 and $15.10 under a Rule 10b5-1 trading plan adopted April 8, 2026.

Following these transactions, Atlas Venture funds associated with him reported holding 169,556 shares of Korro Bio common stock indirectly, with Formela disclaiming Section 16 beneficial ownership except for any pecuniary interest.

Korro Bio, Inc. Chief Operating Officer Todd Chappell reported the sale of 3,168 shares of common stock on June 16, 2026 at a weighted-average price of $10.83 per share. According to the disclosure, this was a mandatory sale solely to satisfy tax withholding obligations arising from the vesting and settlement of restricted stock units granted under the company’s 2023 Stock Option and Incentive Plan. After this tax-related sale, Chappell holds a total of 16,964 shares, which includes 10,066 shares underlying an RSU award scheduled to vest on December 15, 2026, subject to his continued service with the company.

Korro Bio, Inc. Chief Scientific Officer Vincent Loic A reported a sale of 3,418 shares of common stock at a weighted-average price of $10.83 per share. According to the disclosure, this was a mandatory sale solely to satisfy tax withholding obligations from vesting of a restricted stock unit granted under the 2023 Stock Option and Incentive Plan.

After this tax-related transaction, he holds 18,297 shares of common stock, including 10,858 shares issuable upon settlement of an RSU that is scheduled to vest on December 15, 2026, subject to continued service with the company.

Korro Bio, Inc. General Counsel Jeffrey Cerio reported an open-market sale of 6,609 shares of common stock at a weighted-average price of $10.83 per share. According to the filing, this was a mandatory sale solely to satisfy tax withholding obligations from vested restricted stock units under the 2023 equity plan.

After this transaction, Cerio holds 35,293 shares directly, including 20,951 shares underlying restricted stock units that are scheduled to vest on December 15, 2026, if his service with the company continues through that date.

Korro Bio, Inc. Senior Vice President of Finance Oliver Dolan reported an open-market sale of 3,383 shares of common stock on June 16, 2026 at a weighted-average price of $10.83 per share. According to the footnotes, this was a mandatory sale solely to cover tax withholding obligations arising from the vesting and settlement of restricted stock units (RSUs) granted under the company’s 2023 Stock Option and Incentive Plan.

After this transaction, Dolan holds 18,099 shares of common stock directly, which includes 10,741 shares issuable upon settlement of an RSU that is scheduled to vest on December 15, 2026, provided he maintains a continuous service relationship through that date.

Korro Bio director Ali Behbahani received a grant of stock options covering 14,677 shares of common stock at an exercise price of $10.59 per share. These options were awarded at no upfront cost and expire on June 9, 2036.

The options vest in full on the earlier of the one-year anniversary of the grant date or the next annual meeting of stockholders, subject to his continued service as a non-employee director. Following this award, Behbahani holds 14,677 stock options directly.

Korro Bio, Inc. director Rachel Meyers received a grant of stock options as part of her compensation. The award covers 14,677 options to purchase Common Stock at an exercise price of $10.59 per share, all held directly after the transaction.

These options vest in full on the earlier of the one-year anniversary of the grant date or the company’s next annual meeting of stockholders, provided she continues serving as a non-employee director through that date. The options are scheduled to expire on June 9, 2036, giving a long-dated incentive aligned with the company’s share price performance.

Korro Bio, Inc. reported that director Nessan Bermingham received a stock option grant covering 14,677 shares of common stock. The option has an exercise price of $10.59 per share and expires on June 9, 2036. The option vests in full on the earlier of the one-year anniversary of the grant date or the next annual meeting of stockholders, subject to his continued service as a non-employee director.

Korro Bio director Katharine Knobil received a grant of stock options covering 14,677 shares of common stock at an exercise price of $10.59 per share. These options vest in full on the earlier of one year from the grant date or the next annual stockholder meeting, subject to her continued service as a non-employee director, and will expire on June 9, 2036.

Korro Bio director Jean Francois Formela received a stock option grant as equity compensation. The award covers 14,677 shares of common stock at an exercise price of $10.59 per share and expires on June 9, 2036. The option vests in full on the earlier of the one-year anniversary of the grant date or the next annual meeting of stockholders, provided he continues serving as a non-employee director through that vesting date.

Korro Bio director Timothy R. Pearson reported receiving a grant of stock options under the company’s equity plan. The award covers 14,677 options for Common Stock at an exercise price of $10.59 per share, with no cash paid for the grant itself.

The options vest in full on the earlier of the one-year anniversary of the grant date or the next annual meeting of stockholders, provided he continues serving as a non-employee director through that date. Following this grant, Pearson holds 14,677 stock options directly, which expire on June 9, 2036.

Korro Bio, Inc. director and President & CEO Ram Aiyar reported a disposition of common stock primarily tied to equity compensation. On the reported date, 15,152 shares of common stock were sold at a weighted-average price of $12.98 per share solely to satisfy tax withholding obligations arising from the vesting and settlement of a performance stock unit award. Following this tax-related sale, Aiyar directly held 74,848 shares of common stock, and an additional 4,613 shares were held indirectly through The Ram Aiyar Irrevocable Trust, for which he serves as trustee and disclaims beneficial ownership except for any pecuniary interest. The filing also notes that his holdings include 40,000 shares of common stock issuable upon settlement of a restricted stock unit granted under the company’s 2023 equity plan.

Korro Bio director-related funds report small planned share sale. Atlas Venture Fund XI, L.P. and Atlas Venture Opportunity Fund II, L.P., entities associated with director Jean Francois Formela, sold a total of 2,860 shares of Korro Bio common stock at $13.95 per share on May 28, 2026 in open-market transactions under a Rule 10b5-1 trading plan adopted on April 8, 2026.

Following these indirect transactions, Atlas Venture Fund XI, L.P. is shown holding 194,655 shares and Atlas Venture Opportunity Fund II, L.P. is shown holding 939,634 shares of common stock. Formela is a member of the general partner entities and disclaims Section 16 beneficial ownership of these shares except to the extent of any pecuniary interest.

Korro Bio, Inc. President and CEO Ram Aiyar reported an equity award that increased his beneficial holdings. On May 26, 2026, he acquired 50,000 shares of common stock at $12.33 per share, issued upon settlement and vesting of a performance stock unit granted under the company’s 2023 Stock Option and Incentive Plan.

Following this transaction, he beneficially owns 90,000 shares directly, which includes 40,000 shares issuable upon settlement of a previously reported restricted stock unit grant. An additional 4,613 shares are held indirectly by The Ram Aiyar Irrevocable Trust, for which he serves as trustee and disclaims beneficial ownership except to the extent of his pecuniary interest.

Lynx1 Master Fund LP, an entity associated with Lynx1 Capital Management LP and Weston Nichols, reported an indirect open-market purchase of 520 shares of Korro Bio, Inc. common stock at $10.60 per share. Following this transaction, the reporting structure shows 1,538,296 shares held indirectly. Lynx1 Capital Management LP and Mr. Nichols each disclaim beneficial ownership except to the extent of any pecuniary interest.

Korro Bio, Inc. reported that investment entities associated with Rick Yang made significant indirect open-market purchases of its securities. On March 10, 2026, New Enterprise Associates 17, L.P. acquired 242,945 Pre-Funded Warrants at $11.1090 per warrant and 207,100 shares of Common Stock at $11.1100 per share under a Subscription Agreement dated March 9, 2026. Following these transactions, NEA 17 indirectly holds 1,297,893 shares of Common Stock and the Pre-Funded Warrants, while the Reporting Person disclaims beneficial ownership where there is no pecuniary interest. The Pre-Funded Warrants are exercisable at any time, subject to a 9.99% ownership cap that can be adjusted up to 19.99% with 61 days’ prior notice.

SANDELL SCOTT D reported open-market purchase transactions in this Form 4 filing.

Korro Bio, Inc. insider entities linked to Scott D. Sandell indirectly acquired 242,945 Pre-Funded Warrants and 207,100 shares of Common Stock on March 10, 2026, pursuant to a Subscription Agreement dated March 9, 2026.

The Pre-Funded Warrants carry a $0.001 exercise price and are exercisable at any time, subject to a 9.99% ownership cap that can be adjusted up to 19.99% with 61 days’ notice.

New Enterprise Associates 17, L.P., a 10% owner of Korro Bio, Inc., bought additional securities in the company. On March 10, 2026, it acquired 207,100 shares of Common Stock at $11.11 per share and 242,945 Pre-Funded Warrants at $11.109 per warrant pursuant to a Subscription Agreement dated March 9, 2026.

The Pre-Funded Warrants are exercisable at $0.001 per share at any time after issuance but include a beneficial ownership cap that generally limits the holder to 9.99% of Korro Bio’s outstanding Common Stock, which can be adjusted up to 19.99% with 61 days’ prior notice.

Korro Bio, Inc. reported that a 10% owner associated with Carmen Chang made significant indirect open-market purchases of its securities. On March 10, 2026, an entity affiliated with her acquired 242,945 Pre-Funded Warrants at $11.109 per warrant and 207,100 shares of Common Stock at $11.11 per share, totaling 450,045 securities.

The Pre-Funded Warrants were acquired from the company under a Subscription Agreement dated March 9, 2026 and are exercisable at any time, subject to a beneficial ownership cap of 9.99% of outstanding common stock, adjustable up to 19.99% with 61 days’ notice. The transactions are reported as indirect holdings through New Enterprise Associates 17, L.P., and Chang disclaims beneficial ownership of any portion in which she has no pecuniary interest.

Korro Bio, Inc. reported that investment entities associated with director and 10% owner Ali Behbahani acquired additional securities. On March 10, 2026, NEA 17 received 242,945 Pre-Funded Warrants, each exercisable into one share of Common Stock at $0.001 per share, subject to a 9.99% ownership cap that can be raised up to 19.99% with 61 days’ notice. The same day, NEA 17 was also awarded 207,100 shares of Common Stock at $11.11 per share, bringing its indirectly held Common Stock position to 1,297,893 shares. Behbahani is a manager of the NEA 17 general partners and disclaims beneficial ownership of portions in which he has no pecuniary interest.

Korro Bio, Inc. reported that investment entity New Enterprise Associates 17, L.P. acquired additional exposure to its stock through a private subscription. On March 10, 2026, it bought 207,100 shares of common stock at $11.11 per share and 242,945 pre-funded warrants at $11.109 per warrant. The warrants are exercisable at $0.001 per share but include a 9.99% beneficial ownership cap, which the holder may adjust upon 61 days’ notice, not to exceed 19.99%. Following these purchases, indirect holdings include 1,297,893 shares of common stock and the newly acquired warrants. Forest Baskett is a manager of entities controlling NEA 17 and disclaims beneficial ownership where he has no pecuniary interest.

Korro Bio, Inc. reported that an entity associated with major holder Edward T. Mathers bought additional securities. On March 10, 2026, New Enterprise Associates 17, L.P., for which Mathers is an affiliated manager, acquired 242,945 Pre-Funded Warrants at $11.109 per underlying share and 207,100 shares of Common Stock at $11.110 per share in a purchase coded as an open-market transaction and documented in a Subscription Agreement dated March 9, 2026.

The Pre-Funded Warrants are immediately exercisable at an exercise price of $0.001 per share but contain a Beneficial Ownership Limitation that generally caps the holder’s ownership at 9.99% of Korro Bio’s outstanding Common Stock after exercise, with the cap adjustable on 61 days’ notice up to 19.99%. Following these transactions, indirect holdings reported for Common Stock totaled 1,297,893 shares.

Korro Bio, Inc. reported insider-related purchases of both common stock and pre-funded warrants by an entity associated with major holder Mohamad Makhzoumi. On March 10, 2026, New Enterprise Associates 17, L.P. acquired 242,945 pre-funded warrants at $11.1090 per underlying share and 207,100 shares of common stock at $11.1100 per share in open-market or private transactions pursuant to a Subscription Agreement dated March 9, 2026. The pre-funded warrants are exercisable at $0.0010 per share and include a beneficial ownership cap of 9.99%, which the holder may adjust to as high as 19.99% with 61 days’ prior notice.

Korro Bio, Inc. insider Paul Edward Walker, a reported ten percent owner through New Enterprise Associates entities, reported net purchases of Korro Bio securities. An affiliate bought 242,945 Pre-Funded Warrants, each exercisable into one share of Common Stock at an exercise price of $0.001 per share, at a purchase price of $11.109 per warrant.

The same affiliated fund also bought 207,100 shares of Common Stock at $11.11 per share, bringing its indirect Common Stock holdings to 1,297,893 shares following the transactions. All securities are held indirectly by New Enterprise Associates 17, L.P., and Walker disclaims beneficial ownership of any portion in which he has no pecuniary interest.

The Pre-Funded Warrants are immediately exercisable but include a beneficial ownership limitation: they cannot be exercised if doing so would cause the holder and certain related parties to exceed 9.99% of Korro Bio’s outstanding Common Stock, a cap that can be adjusted up to 19.99% with 61 days’ prior notice.

Florence Anthony A. Jr. reported open-market purchase transactions in this Form 4 filing.

Korro Bio, Inc. disclosed that investment fund New Enterprise Associates 17, L.P. (NEA 17), an entity associated with 10% owner Anthony A. Florence Jr., entered into a Subscription Agreement with the company. On March 10, 2026, NEA 17 acquired 242,945 Pre-Funded Warrants at $11.109 per underlying share and 207,100 shares of Common Stock at $11.11 per share. Following the transaction, NEA 17 held 242,945 pre-funded warrants (each exercisable into one share of Common Stock at $0.001 per share) and 1,297,893 shares of Common Stock. The pre-funded warrants are exercisable at any time but include a 9.99% beneficial ownership cap, which the holder may adjust upon 61 days' notice, not to exceed 19.99%. Florence is a manager of the NEA 17 general partner and disclaims beneficial ownership of portions of these securities in which he has no pecuniary interest.

Korro Bio, Inc. reported that President and CEO Ram Aiyar received new equity awards on February 2, 2026. He was granted 40,000 shares of common stock through restricted stock units under the 2023 Stock Option and Incentive Plan, vesting 50% on August 3, 2026 and 50% on February 1, 2027, subject to continued service.

He was also granted a stock option for 80,000 shares of common stock at an exercise price of $13.05, vesting in 48 equal monthly installments starting February 2, 2026 and expiring February 1, 2036. Separately, 4,613 common shares are held indirectly by The Ram Aiyar Irrevocable Trust, for which he serves as trustee and disclaims full beneficial ownership.

Korro Bio, Inc. reported that its Chief Scientific Officer, Vincent Loic A, received a grant of stock options on February 2, 2026. The award covers 35,000 stock options with an exercise price of $13.05 per share for Korro Bio common stock.

The options vest in 48 equal monthly installments starting on February 2, 2026, and each monthly vesting is conditioned on the executive’s continued service on that date. After this grant, the officer beneficially owns 35,000 derivative securities directly.

Korro Bio, Inc. reported that Senior Vice President of Finance Dolan Oliver received a stock option award. On February 2, 2026, Oliver was granted an option to buy 15,000 shares of Korro Bio common stock at an exercise price of $13.05 per share, expiring February 1, 2036.

The option vests in 48 equal monthly installments starting February 2, 2026, contingent on Oliver’s continued service with the company on each vesting date. After this grant, Oliver beneficially owns 15,000 derivative securities directly.

Korro Bio, Inc. reported that its General Counsel, Jeffrey Cerio, received a grant of stock options covering 23,000 shares of common stock. The options have an exercise price of $13.05 per share and were awarded on February 2, 2026.

These options vest in 48 equal monthly installments starting on February 2, 2026, and each vesting date requires Mr. Cerio to remain in service with the company. Following this grant, he beneficially holds options for 23,000 shares, all in direct ownership.

Korro Bio, Inc. reported that Chief Operating Officer Todd Chappell received a stock option award for 38,000 derivative securities described as a stock option (right to buy) common stock. The option has an exercise price of $13.05 per share and was granted on February 2, 2026.

The grant was made for no purchase price and leaves Chappell with 38,000 stock options beneficially owned directly. These options expire on February 1, 2036 and vest in 48 equal monthly installments starting February 2, 2026, conditioned on his continued service at each vesting date.

Korro Bio, Inc. (KRRO) granted its chief operating officer 20,132 restricted stock units linked to its common stock. These RSUs were acquired at a reported price of $0.00 and leave the officer beneficially owning 20,132 shares directly after the transaction. The award was made under the company’s 2023 Stock Option and Incentive Plan and will vest in two equal installments: 50% on June 15, 2026 and 50% on December 15, 2026, provided the officer maintains a continuous Service Relationship through each vesting date.

Korro Bio's Chief Scientific Officer received a grant of 21,715 shares of common stock on December 15, 2025, reported as an acquisition at a price of $0.00 per share. Following this transaction, the officer beneficially owns 21,715 shares directly.

The shares are issuable upon settlement of a restricted stock unit (RSU) award granted under the company’s 2023 Stock Option and Incentive Plan. The RSUs will vest in two equal installments: 50% on June 15, 2026 and 50% on December 15, 2026, provided the officer maintains a continuous Service Relationship through each vesting date.

Korro Bio, Inc. reported an equity award to its General Counsel in an insider ownership filing. Officer Jeffrey Cerio acquired 41,902 shares of common stock at a price of $0.00, reflecting a grant tied to restricted stock units under the company’s 2023 Stock Option and Incentive Plan.

The filing explains that these shares are issuable upon settlement of a restricted stock unit (RSU) award that will vest in two equal installments: 50% on June 15, 2026 and 50% on December 15, 2026, if he maintains a continuous service relationship through each vesting date. After this grant, he is shown as beneficially owning 41,902 shares directly.

Korro Bio reported an insider equity award to its Senior Vice President, Finance. On December 15, 2025, the officer received 21,482 shares of common stock issuable upon settlement of a restricted stock unit (RSU) grant at a reported price of $0.00 per share under the company’s 2023 Stock Option and Incentive Plan.

The RSUs will vest in two equal installments: 50% on June 15, 2026 and 50% on December 15, 2026, provided the officer maintains a continuous Service Relationship as defined in the plan through each vesting date. Following this grant, the reporting person beneficially owns 21,482 shares of Korro Bio common stock issuable upon RSU settlement, held directly.