Korsana Biosciences, Inc. filed a Form S-8 registration statement with the SEC on November 9, 2026, registering a combined 13,726,188 shares of common stock issuable under three equity compensation plans following its September 2026 merger with the former private Korsana Biosciences entity.

Key Highlights

  • Three plans covered: The registration covers the 2026 Stock Incentive Plan, the 2026 Employee Stock Purchase Plan, and the 2025 Equity Incentive Plan.
  • 2026 Stock Incentive Plan: 6,092,348 shares of common stock, no par value per share, are registered under this plan.
  • 2026 Employee Stock Purchase Plan: 550,512 shares of common stock are registered under this plan.
  • 2025 Equity Incentive Plan: 7,083,328 shares are registered, covering assumed and converted stock options originally issued by the pre-merger private entity.
  • Merger completed September 8, 2026: The company, formerly known as Cyclerion Therapeutics, Inc., completed its combination with the private Delaware corporation formerly known as Korsana Biosciences, Inc.
  • Filer classification: The registrant identified itself as a non-accelerated filer and a smaller reporting company.

Korsana Biosciences Registers Post-Merger Equity Compensation Shares

According to the filing, Korsana Biosciences, Inc. (NASDAQ:KRSA), a Massachusetts corporation formerly known as Cyclerion Therapeutics, Inc., completed a business combination on September 8, 2026, with an entity formerly known as Korsana Biosciences, Inc., a private Delaware corporation, pursuant to an Agreement and Plan of Merger and Reorganization dated April 1, 2026, and amended on April 17, 2026. The merger involved two wholly owned subsidiaries of the registrant: Cariboos Merger Sub Corp. and Cariboos Merger Sub II, LLC.

The Form S-8 registration statement registers a total of 13,726,188 shares of common stock, no par value per share, across three plans. As disclosed in the filing, 6,092,348 shares are issuable under the 2026 Stock Incentive Plan, 550,512 shares are issuable under the 2026 Employee Stock Purchase Plan, and 7,083,328 shares are issuable under the 2025 Equity Incentive Plan. The filing states that the 2025 Plan shares correspond to outstanding stock options that were originally issued by the pre-merger private entity, assumed by the registrant, and converted into options to purchase shares of the registrant's common stock in connection with the merger.

The filing incorporates by reference several previously filed documents, including the registrant's prospectus filed July 24, 2026, under the Securities Act relating to Form S-4 (File No. 333-295175), Quarterly Reports on Form 10-Q for the periods ended March 31, June 30, and September 30, 2026, and Current Reports on Form 8-K filed on January 6, April 1, August 25, August 27, and September 11, 2026. Jonathan Violin, Ph.D., is identified as Chief Executive Officer and President, and serves as the named agent for service. Gibson, Dunn & Crutcher LLP in Dallas, Texas, is listed as counsel.

What Was Disclosed

Korsana Biosciences filed a Form S-8 on November 9, 2026, registering 13,726,188 shares of common stock issuable under three equity compensation plans established in connection with or following its September 8, 2026, merger with a private predecessor entity.