Boundless Bio tightens Serapha merger mechanics with August 28 amendment
The agreement governing Boundless Bio's (BOLD) planned acquisition of Serapha Bio, Inc. was revised on August 28, 2026, when the parties executed Amendment No. 1 to the June 22 Agreement and Plan of Merger and Reorganization. Boulder Merger Sub Corp., a wholly owned Boundless Bio subsidiary, will merge into Serapha, leaving Serapha as the surviving entity under BOLD's umbrella. The next confirmable milestone is the Company Pre-Closing Financing, which the amendment references but does not size.
Key takeaways
- Boundless Bio (BOLD) and Serapha Bio executed Amendment No. 1 on August 28, 2026 to their June 22 merger agreement, under which Boulder Merger Sub Corp. will merge into Serapha, leaving Serapha as the surviving entity.
- The amendment converts Serapha's vested and unvested RSU awards into Boundless Bio RSU awards at closing, with share counts adjusted by the original Exchange Ratio.
- Holders who would breach their Beneficial Ownership Limitation can elect pre-funded warrants at an exercise price of $0.00001 per share instead of receiving merger shares.
- The vote threshold for expanding Boundless Bio's authorized share count changed from a majority of shares outstanding and entitled to vote to a majority of shares properly cast.
- Closing depends on the Company Pre-Closing Financing (unsized in the filing) and on Serapha's license agreement with YolTech Therapeutics, disruption of which is flagged as a standalone closing risk.
The agreement governing Boundless Bio's (BOLD) planned acquisition of Serapha Bio, Inc. was revised on August 28, 2026, when the parties executed Amendment No. 1 to the June 22 Agreement and Plan of Merger and Reorganization. Boulder Merger Sub Corp., a wholly owned Boundless Bio subsidiary, will merge into Serapha, leaving Serapha as the surviving entity under BOLD's umbrella. The next confirmable milestone is the Company Pre-Closing Financing, which the amendment references but does not size.
The mechanics the amendment adds
Three changes carry operational weight. Serapha restricted stock unit awards, vested and unvested alike, will convert at closing into Boundless Bio RSU awards rather than settle for cash; the share count on each award adjusts by the Exchange Ratio specified in the original agreement. Holders who would breach their applicable Beneficial Ownership Limitation on receiving shares as merger consideration can elect pre-funded warrants instead, at an exercise price of $0.00001 per share. The third change gets less attention than it deserves: the vote threshold for expanding Boundless Bio's authorized share count shifts from a majority of shares outstanding and entitled to vote to a majority of shares properly cast. In any deal where retail and small institutional participation is unpredictable, that distinction carries real consequence.
The Exchange Ratio is unchanged from June, though the filing flags it as a live variable: adjustments prior to closing could shift the ownership percentages of both Boundless Bio's and Serapha's stockholders from current expectations. An anticipated cash dividend is referenced in the risk disclosures without a dollar figure attached. Boundless Bio, headquartered in La Jolla, California and listed on the Nasdaq Global Select Market, is classified as an emerging growth company.
What to watch
Two closing dependencies are named directly. The Company Pre-Closing Financing must close; this filing gives no size for it. Separately, Serapha's intellectual property position carries a specific dependency flagged in the risk disclosures: the company relies on a license agreement with YolTech Therapeutics, and any disruption there is identified as a standalone closing risk. The 8-K, filed as a Rule 425 written communication under the Securities Act, attaches the amendment as Exhibit 2.1 to the Current Report.
Related reading
Filed by the newsroom of MarketPR on August 31, 2026. Source: sec.gov. Indicative figures are not investment advice.