SCHEDULE: Mangrove Partners Cuts Mereo BioPharma Stake Below 5%

Mangrove Partners IM, LLC and Nathaniel August have reduced their beneficial ownership in Mereo BioPharma Group plc to 4.9%, signaling a partial divestment.

Summary

• Mangrove Partners IM, LLC and Nathaniel August, as reporting persons, have filed an Amendment No. 1 to Schedule 13G regarding their beneficial ownership in Mereo BioPharma Group plc.
• The reporting persons now collectively beneficially own 38,952,900 ordinary shares of Mereo BioPharma Group plc, which are represented by 7,790,580 American Depositary Shares (ADRs).
• This ownership stake represents 4.9% of the class of securities, falling below the 5% threshold.
• The calculation of the percentage is based on 795,484,404 ordinary shares outstanding as of August 12, 2025, as reported by the Issuer in its 10-Q.
• The event requiring this filing occurred on September 30, 2025, with the statement signed on November 14, 2025.
• Mangrove Partners IM, LLC serves as the investment manager for The Mangrove Partners Master Fund, Ltd., which directly holds the shares.
• Nathaniel August, President of Mangrove Partners IM, LLC, also claims beneficial ownership.
• An internal restructuring within Mangrove Partners occurred on March 14, 2024, where Nathaniel August and other members contributed interests to Mangrove Holding, Inc. and then sold equity to the Mangrove Retirement Savings Plan.

Sentiment

Score: 3

Explanation: The sentiment is negative due to the reduction in beneficial ownership by a significant institutional investor to below 5%. This often implies a loss of conviction or a strategic shift away from the issuer, which can be perceived negatively by the market.

Negatives

• The reduction in beneficial ownership by a significant institutional investor to below 5% typically signals a diminished outlook or a strategic reallocation of capital away from the issuer.

Future Outlook

This filing does not contain forward-looking statements or guidance from the issuer, Mereo BioPharma Group plc. It solely reports a change in beneficial ownership by an institutional investor.

Management Comments

• Nathaniel August, President of Mangrove Partners IM, LLC, certified that the securities were acquired and are held in the ordinary course of business and not for the purpose or with the effect of changing or influencing the control of the issuer, nor in connection with any transaction having that purpose or effect, other than activities solely in connection with a nomination under Rule 14a-11.

Industry Context

This filing reflects a change in an institutional investor's position within the biopharmaceutical sector. Such divestments by significant shareholders can influence market perception of a company's prospects, potentially signaling a shift in investor confidence or a reallocation of capital within the competitive biopharma landscape.

Stakeholder Impact

• Shareholders may perceive the reduction in a significant institutional stake as a negative signal, potentially leading to decreased investor confidence and downward pressure on the stock price.
• The company's management might face increased scrutiny regarding its performance or strategic direction if a major investor is reducing its exposure.

Key Dates

Recommendation

The reduction in beneficial ownership by Mangrove Partners IM, LLC and Nathaniel August to below 5% suggests a strategic divestment. This move by a significant institutional investor could signal a diminished outlook for the company or a reallocation of capital, which typically warrants a re-evaluation of the investment thesis and potentially a reduction in exposure.

Keywords

Mereo BioPharma Group plc, Mangrove Partners, Schedule 13G, Beneficial Ownership, Institutional Investor, Stake Reduction, Biopharma, ADRs