Day One Biopharmaceuticals Completes Acquisition of Mersana Therapeutics, Leading to Delisting

summarizeSummary

Day One Biopharmaceuticals has successfully completed its tender offer and acquisition of Mersana Therapeutics, with Mersana becoming a wholly-owned subsidiary and its stock delisting from Nasdaq.

check_boxKey Events

• Acquisition Finalized

  Day One Biopharmaceuticals completed its acquisition of Mersana Therapeutics, Inc. on January 6, 2026.

• Tender Offer Successful

  The tender offer expired on January 5, 2026, with 60.57% of outstanding shares validly tendered, satisfying the minimum condition.

• Merger Consummated

  Mersana has merged with Emerald Merger Sub, Inc., becoming a direct wholly-owned subsidiary of Day One Biopharmaceuticals.

• Delisting from Nasdaq

  Mersana's common stock will cease trading on Nasdaq and will be deregistered under the Exchange Act.

auto_awesomeAnalysis

This filing confirms the finalization of the acquisition of Mersana Therapeutics by Day One Biopharmaceuticals. The tender offer successfully met its minimum conditions, leading to the merger and subsequent delisting of Mersana's common stock. Shareholders will receive $25.00 per share in cash plus a contingent value right (CVR) potentially worth up to an additional $30.25 per share, totaling up to $55.25 per share. This event fundamentally alters the investment thesis for Mersana shareholders, as the company will no longer trade independently.