Boundless Bio enters merger agreement with Serapha Bio in all-stock transaction
Boundless Bio, Inc. entered into a definitive merger agreement with Serapha Bio, Inc. on June 22, 2026, under which Serapha will merge with a Boundless subsidiary, with Serapha surviving as a wholly owned subsidiary of Boundless. The combined company will operate as Serapha Bio, Inc. and is expected to trade on Nasdaq under ticker AATD. Serapha has secured approximately $230 million in concurrent private investment (approximately $138 million Series A already funded, approximately $92 million pre-closing), co-led by RA Capital and RTW Investments. Prior to closing, Boundless expects to declare a cash dividend of approximately $44 to $48 million to pre-merger Boundless stockholders. The transaction is expected to close in the fourth quarter of 2026, subject to stockholder approvals and other customary conditions. Post-closing, pre-merger Boundless stockholders are expected to own approximately 3.69% of the combined company and pre-merger Serapha stockholders (including pre-closing financings investors) approximately 96.31%.
Key facts
- Merger agreement dated June 22, 2026 by and among Boundless Bio, Inc., Boulder Merger Sub Corp., and Serapha Bio, Inc.
- Pre-closing financing of approximately $92,000,000 in aggregate purchase price (plus approximately $138,000,000 Series A already funded)
- Pre-merger Boundless stockholders expected to own approximately 3.69% of combined company; pre-merger Serapha stockholders approximately 96.31%
- Boundless cash dividend of approximately $44 to $48 million to pre-merger stockholders expected prior to closing
- Expected closing in fourth quarter of 2026
- Combined company to operate as Serapha Bio, Inc. and trade on Nasdaq under ticker AATD
- Exchange Ratio computed as quotient of Company Merger Shares divided by Company Outstanding Shares, using Company Valuation and Parent Valuation as defined
- Approximately 75% workforce reduction at Boundless with estimated one-time costs of approximately $3.0 million to $5.0 million
- All Boundless Bio outstanding stock options with exercise price greater than $8.00 cancelled for no consideration
- Zachary D. Hornby ceased role as President and CEO effective July 1, 2026; Jessica Oien appointed President and principal executive officer
Why it matters
Boundless Bio completes a strategic combination with Serapha Bio, transferring control to Serapha's investors and positioning the combined entity as a gene-editing-focused biotech company advancing SERP-01 for Alpha-1 Antitrypsin Deficiency, while Boundless shareholders receive both a substantial cash dividend and minority equity stake in the public successor company.
Share
Derived from 8-K filed 2026-06-23. Not investment advice. View the source filing on SEC.gov →