Adage Capital Management, L.P., along with managing members Robert Atchinson and Phillip Gross, filed a Schedule 13G with the SEC on November 12, 2026, disclosing beneficial ownership of 1,000,000 shares of Korro Bio, Inc. common stock as of September 30, 2026.

Key Highlights

  • Aggregate beneficial ownership: Each of the three reporting persons disclosed beneficial ownership of 1,000,000 shares of Korro Bio, Inc. common stock.
  • Percent of class: The 1,000,000 shares represent 6.79% of outstanding common stock, calculated on a base of 14,725,646 shares outstanding as of August 5, 2026.
  • No sole voting or dispositive power: All 1,000,000 shares are reported with 0 sole voting power and 0 sole dispositive power; all voting and dispositive power is shared among the reporting persons.
  • Shares held by: The shares are directly held by Adage Capital Partners, L.P., with Adage Capital Management, L.P. acting as investment manager.
  • Triggering event date: The event requiring this filing occurred on September 30, 2026.
  • Ordinary course certification: The filing states the securities "were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer."

Adage Capital Management Reports Shared Ownership of Korro Bio Shares

According to the Schedule 13G filed November 12, 2026, three reporting persons disclosed a combined beneficial interest in 1,000,000 shares of Korro Bio, Inc. (CUSIP: 500946108) common stock, par value $0.001 per share. The reporting persons are Adage Capital Management, L.P. (ACM), a Delaware limited partnership classified as an investment adviser and limited partnership; Robert Atchinson, a U.S. citizen; and Phillip Gross, a U.S. citizen. All three share a business address of 200 Clarendon Street, 52nd Floor, Boston, Massachusetts 02116.

The filing states that ACM serves as investment manager of Adage Capital Partners, L.P. (ACP), which directly holds the reported shares. Robert Atchinson and Phillip Gross each serve as managing members of Adage Capital Advisors, L.L.C. and related general partner entities within the Adage structure, as described in Item 2(a) of the filing. Each reporting person reports shared voting power of 1,000,000 shares and shared dispositive power of 1,000,000 shares, with sole voting and sole dispositive power of zero for each.

The 6.79% ownership figure is based on 14,725,646 shares of Korro Bio common stock outstanding as of August 5, 2026, as reported in the company's Quarterly Report on Form 10-Q for the period ended June 30, 2026, filed with the SEC on August 6, 2026, according to the filing. The filing further notes that it "should not be construed in and of itself as an admission by any Reporting Person as to beneficial ownership of the securities reported herein."

What Was Disclosed

Adage Capital Management, L.P., Robert Atchinson, and Phillip Gross filed a Schedule 13G reporting shared beneficial ownership of 1,000,000 shares, or 6.79%, of Korro Bio, Inc. common stock, triggered by an event on September 30, 2026.