Form 4: Mineralys Director Plans $43.35M Stock Sale

A director and 10% owner of Mineralys Therapeutics, Brian Taylor Slingsby, plans to sell 1,000,000 shares of common stock for $43.35 per share on November 20, 2025, under a Rule 10b5-1 plan.

Summary

• Brian Taylor Slingsby, a Director and 10% Owner of Mineralys Therapeutics, Inc. (MLYS), plans to sell 1,000,000 shares of common stock.
• The transaction is scheduled for November 20, 2025, at a price of $43.35 per share.
• The total value of the planned sale is $43,350,000.
• Following this transaction, 7,903,838 shares will be beneficially owned indirectly by Catalys Pacific Fund, LP.
• The sale is being made pursuant to a Rule 10b5-1(c) plan, which allows insiders to pre-arrange sales to avoid accusations of trading on material non-public information.
• Brian Taylor Slingsby, through Catalys Pacific, LLC and Catalys Pacific Fund GP, LP, may be deemed to have voting and investment power over the shares held by Catalys Pacific Fund, LP, but disclaims beneficial ownership except for any pecuniary interest.

Sentiment

Score: 5

Explanation: The planned sale of a significant number of shares by a director and 10% owner is generally a neutral to slightly negative signal. However, the explicit mention of a Rule 10b5-1 plan mitigates the negative perception, as it indicates the sale was pre-arranged and not based on recent material non-public information.

Positives

• The planned sale is pursuant to a Rule 10b5-1(c) plan, indicating it was pre-arranged and not based on recent material non-public information.

Negatives

• A significant planned sale of 1,000,000 shares by a director and 10% owner could be perceived negatively by some investors, despite the 10b5-1 plan.

Risks

• Investor perception of a large insider sale, even if pre-planned, could lead to negative sentiment.

Future Outlook

The filing details a pre-planned future transaction scheduled for November 20, 2025, under a Rule 10b5-1 plan, but does not provide broader forward-looking statements or guidance for the company's operations or financial performance.

Management Comments

• Brian Taylor Slingsby disclaims beneficial ownership of such shares, except to the extent of any pecuniary interest therein.

Industry Context

This filing reports an individual insider transaction and does not provide broader industry context or trends.

Comparison to Industry Standards

• Not applicable as this filing details a specific insider transaction rather than company performance metrics that can be benchmarked against industry standards or competitors.

Related Party Transactions

• The shares are held indirectly by Catalys Pacific Fund, LP, whose general partner is Catalys Pacific Fund GP, LP. Brian Taylor Slingsby is the managing partner of Catalys Pacific, LLC, which is the general partner of Catalys Pacific Fund GP, LP. This establishes a clear indirect relationship and control over the shares.

Stakeholder Impact

• Shareholders may interpret the planned sale by a director and 10% owner as a signal, potentially influencing short-term stock price movements, although the 10b5-1 plan mitigates concerns about insider information.

Next Steps

• The planned sale of 1,000,000 shares is scheduled to occur on November 20, 2025.

Key Dates

Recommendation

The planned sale by a director and 10% owner, while significant in volume, is explicitly stated to be under a Rule 10b5-1 plan. This suggests the transaction is a pre-scheduled liquidity event rather than a reaction to new material information about the company's fundamentals. Therefore, it does not provide a strong signal for a 'buy' or 'sell' recommendation based solely on this filing, warranting a 'hold' position for existing investors.

Keywords

MLYS, Mineralys Therapeutics, insider trading, Form 4, stock sale, director, 10% owner, Rule 10b5-1