SCHEDULE: Sofinnova Reduces Abivax Stake, Sells 1 Million ADSs

Sofinnova Crossover I SLP and related entities have reduced their beneficial ownership in Abivax S.A. by selling approximately 1 million American Depositary Shares (ADS) across two days in January 2026.

Summary

• Sofinnova Crossover I SLP (SC), along with its management company Sofinnova Partners SAS (SP SAS) and its investment committee members, reported a reduction in their beneficial ownership of Abivax S.A. Ordinary Shares and American Depositary Shares (ADS).
• SC sold a total of 950,000 ADSs on January 12, 2026, at weighted average prices ranging from $118.27 to $142.00 per share.
• An additional 50,000 ADSs were sold on January 13, 2026, at weighted average prices ranging from $119.51 to $123.04 per share.
• As of January 14, 2026, SC directly held 3,334,739 Ordinary Shares, representing approximately 4.3% of Abivax's outstanding Ordinary Shares.
• The reporting persons collectively hold 6,399,478 voting rights, which represents approximately 7.7% of Abivax's outstanding voting rights, based on 82,688,932 voting rights as of November 30, 2025.
• The ownership percentages are based on 78,398,795 Ordinary Shares outstanding as of November 30, 2025.
• The shares were originally acquired for investment purposes, and the reporting persons retain the right to change their investment intent, including acquiring or disposing of additional securities.

Sentiment

Score: 3

Explanation: The sentiment is moderately negative due to a significant reduction in stake by a major institutional investor, which can signal reduced confidence or a strategic shift away from the company. While the sales occurred at favorable prices for the seller, the act of selling itself by a large holder is typically viewed negatively for the issuer's stock.

Positives

• The sales of American Depositary Shares (ADS) were executed at favorable weighted average prices, ranging from $118.27 to $142.00 on January 12, 2026, and $119.51 to $123.04 on January 13, 2026, indicating strong market demand at the time of sale for the seller.

Negatives

• A significant institutional investor, Sofinnova Crossover I SLP, has reduced its stake in Abivax S.A. by selling approximately 1 million ADSs, which could be perceived as a negative signal regarding the company's near-term prospects or valuation by other investors.
• The beneficial ownership of Ordinary Shares has decreased to 4.3% of the outstanding shares, down from a previously higher stake, indicating a reduced conviction or a portfolio rebalancing away from Abivax.

Risks

• The reduction in stake by a major investor could lead to increased selling pressure on Abivax's stock as other investors may interpret this as a lack of confidence.
• The reporting persons retain the right to further change their investment intent, including selling additional shares, which introduces uncertainty regarding future stock performance.

Future Outlook

The reporting persons explicitly state they retain the right to change their investment intent, which includes potentially acquiring additional Ordinary Shares or other securities of Abivax, or selling all or part of their currently beneficially owned securities. They may also consider and formulate plans regarding matters described in Items 4(a)-(j) of Schedule 13D instructions, and engage in discussions with Abivax management or board.

Industry Context

This filing reflects a significant portfolio adjustment by a venture capital firm specializing in life sciences, Sofinnova, in a publicly traded biotechnology company, Abivax. Such sales by institutional investors can influence market perception within the biotech sector, particularly for companies in clinical development stages, as they may signal a shift in investment strategy or a realization of gains.

Legal Proceedings

• None of the Reporting Persons have been convicted in any criminal proceeding (excluding traffic violations or similar misdemeanors) during the last five years.
• None of the Reporting Persons have been a party to a civil proceeding of a judicial or administrative body of competent jurisdiction that resulted in a judgment, decree, or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws during the last five years.

Stakeholder Impact

• Shareholders: The reduction in stake by a significant institutional investor could lead to negative market sentiment and potentially impact the share price.
• Investment Community: The filing provides transparency regarding a major investor's reduced position, influencing how other institutional and retail investors perceive Abivax.

Next Steps

• The Reporting Persons may consider acquiring additional Ordinary Shares or other securities of Abivax.
• The Reporting Persons may sell or otherwise dispose of all or part of the Ordinary Shares or other securities of Abivax beneficially owned by them.
• The Reporting Persons may engage in ordinary course transactions with financial institutions regarding Abivax securities.
• The Reporting Persons may formulate plans or proposals related to Abivax's corporate matters and hold discussions with management or the board.

Key Dates

Recommendation

The significant reduction in stake by a major institutional investor like Sofinnova is a notable event that typically signals a cautious outlook or a strategic portfolio rebalancing. While the sales were executed at strong prices for the seller, the decrease in institutional ownership could exert downward pressure on the stock or indicate a lack of strong catalysts. However, without further information on Abivax's operational performance or specific reasons for Sofinnova's divestment beyond 'investment purposes,' a 'hold' recommendation is prudent. Investors should monitor Abivax's upcoming financial results and pipeline developments, as well as any further changes in institutional ownership, before making definitive buy or sell decisions.

Keywords

Abivax, Sofinnova, Schedule 13D, Beneficial Ownership, ADS Sales, Biotechnology Investment, Shareholder Activity, Institutional Investor