SCHEDULE: Adage Capital Exits 89bio Stake Amid Tender Offer

Adage Capital Management and its principals have fully divested their 13.1 million shares in 89bio, Inc. through a tender offer at $14.50 cash per share plus a contingent value right.

Summary

• Adage Capital Management, L.P., Robert Atchinson, and Phillip Gross (the "Reporting Persons") have filed an Amendment No. 1 to their Schedule 13D, signifying an "exit filing."
• The Reporting Persons no longer beneficially own any shares of 89bio, Inc. Common Stock, with their aggregate ownership now at 0%.
• On October 29, 2025, the Reporting Persons tendered all of their 13,097,587 shares of Common Stock into a tender offer.
• The tender offer was made pursuant to a Merger Agreement at an offer price of $14.50 per share in cash, plus one non-tradeable contingent value right per share.
• Prior to the tender, the Reporting Persons engaged in open market sales of Common Stock between October 27, 2025, and October 29, 2025, at weighted average prices ranging from $14.8150 to $14.8400 per share.

Sentiment

Score: 4

Explanation: The sentiment is slightly negative for the Reporting Persons' exit price, as the cash component of the tender offer was below recent open market sale prices. However, the overall sentiment is neutral as it represents a completed transaction and an exit for the reporting entity.

Positives

• The tender offer provided a clear liquidity event for the Reporting Persons, allowing them to fully divest their significant stake in 89bio, Inc.

Negatives

• The cash component of the tender offer price ($14.50 per share) was lower than the open market prices at which the Reporting Persons were selling shares just prior to the tender (ranging from $14.8150 to $14.8400).
• The contingent value right received as part of the tender offer is non-tradeable, limiting its immediate liquidity and valuation.

Future Outlook

The filing indicates the completion of a tender offer for 89bio, Inc. shares, leading to the full divestment by the Reporting Persons. This suggests the company is moving towards the final stages of a merger, with the contingent value right representing potential future value for tendering shareholders.

Industry Context

This filing reflects a significant institutional investor's exit from a biotechnology company, likely in anticipation or completion of a corporate acquisition. Such divestments by major holders are common during merger and acquisition processes, as investors lock in gains or manage portfolio changes ahead of a company going private or being absorbed.

Stakeholder Impact

• Shareholders who tendered their shares received $14.50 in cash and one non-tradeable contingent value right per share, providing a defined exit.
• Shareholders who did not tender their shares will remain holders of 89bio, Inc. and will be subject to the terms and outcomes of the ongoing merger process, including the value realization of the contingent value rights.

Next Steps

• The non-tradeable contingent value right will mature based on future events or milestones related to the merger agreement, as described in 89bio, Inc.'s SEC filings.

Key Dates

Recommendation

A major institutional holder has fully exited their position in 89bio, Inc. through a tender offer, with the cash component of the offer being lower than recent open market sale prices. This signals that a significant investor has chosen to divest, potentially indicating a belief that the immediate upside is limited or that the tender offer, despite its lower cash component, was a preferred exit strategy given the overall merger context. For other investors, this could be a signal to consider selling, especially if they can achieve a better price in the open market or if they are not confident in the future value of the non-tradeable contingent value right.

Keywords

89bio Inc, Adage Capital Management, Schedule 13D/A, Tender Offer, Merger Agreement, Exit Filing, Beneficial Ownership, Common Stock, Contingent Value Right