Form 4: Mirum Director Sells Shares Under 10b5-1 Plan

Mirum Pharmaceuticals Director Saira Ramasastry exercised options and sold 5,000 shares of common stock for $80.00 per share under a pre-arranged 10b5-1 plan.

Summary

• Saira Ramasastry, a Director at Mirum Pharmaceuticals, Inc., executed transactions on December 22, 2025.
• Exercised 5,000 stock options at an exercise price of $23.51 per share. These options were fully vested.
• Immediately after exercising, 5,000 shares of common stock were acquired at $23.51 per share.
• Subsequently, 5,000 shares of common stock were disposed of (sold) at a price of $80.00 per share.
• The transactions were conducted pursuant to a Rule 10b5-1 Plan adopted on September 18, 2025.
• Following these transactions, the reporting person beneficially owns 0 shares of common stock directly and 10,000 stock options directly.

Sentiment

Score: 5

Explanation: The sentiment is neutral. While an insider sale can sometimes be viewed negatively, the fact that it was executed under a pre-arranged 10b5-1 plan mitigates concerns about it being a signal of lack of confidence. It's a routine personal financial management event for the director.

Positives

• The sale was executed at a significantly higher price ($80.00) than the option exercise price ($23.51), indicating a profitable transaction for the insider.
• The transaction was pre-planned under a Rule 10b5-1 plan, suggesting it was not based on new, non-public information.

Negatives

• An insider (Director) sold a significant number of shares, which could be interpreted as a lack of confidence, although mitigated by the 10b5-1 plan.
• The direct beneficial ownership of common stock by the reporting person is now 0 shares, though they retain 10,000 stock options.

Future Outlook

No forward-looking statements or guidance are provided in this Form 4 filing, which solely reports insider transactions.

Industry Context

This insider transaction is a routine disclosure for a publicly traded pharmaceutical company. It reflects an individual director's portfolio management rather than a broader industry trend or specific company performance indicator, especially given it was pre-planned.

Stakeholder Impact

• Shareholders: The sale by a director could be viewed with slight caution, but the pre-planned nature (10b5-1) suggests it's not based on new negative information, thus limiting significant impact on shareholder sentiment.
• Employees/Customers/Suppliers/Creditors: No direct impact on these stakeholders is indicated by this routine insider transaction.

Key Dates

Recommendation

This Form 4 filing reports a routine insider transaction by a director, Saira Ramasastry, involving the exercise of stock options and the subsequent sale of shares under a pre-arranged 10b5-1 plan. While an insider sale might typically raise concerns, the existence of a 10b5-1 plan indicates the transaction was scheduled in advance and not based on recent, non-public information. Therefore, this specific filing does not provide new fundamental information to warrant a change in investment recommendation. Investors should continue to 'hold' based on broader company fundamentals and market conditions, not solely on this routine insider disclosure.

Keywords

Mirum Pharmaceuticals, MIRM, Form 4, Insider Trading, Stock Option Exercise, Share Sale, Saira Ramasastry, 10b5-1 Plan, Director Transaction