Form 4: Mirum Pharma Director Sells Shares After Option Exercise

Mirum Pharmaceuticals Director Saira Ramasastry exercised stock options and subsequently sold a portion of the acquired shares under a pre-arranged 10b5-1 plan.

Summary

• Saira Ramasastry, a Director of Mirum Pharmaceuticals, Inc. (MIRM), reported transactions on December 18, 2025.
• Exercised stock options to acquire 2,000 shares of common stock at an exercise price of $23.51 per share.
• Subsequently sold 1,000 shares of common stock at $69.46 per share.
• Also sold another 1,000 shares of common stock at $70.00 per share.
• All reported transactions were executed pursuant to a Rule 10b5-1 trading plan adopted on September 18, 2025.
• Following these transactions, the reporting person directly owns 0 shares of common stock and 15,000 stock options.

Sentiment

Score: 5

Explanation: The filing reports a routine insider transaction under a pre-arranged plan, which is generally considered neutral in terms of company-specific sentiment. It does not provide new fundamental information about the company's performance or outlook.

Positives

• The exercise of stock options indicates the director realized value from their compensation.
• The sales were executed at significantly higher prices ($69.46 and $70.00) than the exercise price ($23.51), indicating a profitable transaction for the insider.
• The transactions were conducted under a pre-arranged Rule 10b5-1 plan, which suggests a planned, non-discretionary sale rather than a reaction to new, undisclosed information.

Negatives

• Insider selling, even under a 10b5-1 plan, can sometimes be perceived negatively by the market, as it reduces the insider's direct equity stake.

Future Outlook

This filing does not contain any forward-looking statements or guidance regarding the company's future outlook.

Industry Context

This filing reports a routine insider transaction for a director of a pharmaceutical company. Such transactions are common for executives and directors managing their equity compensation and personal finances, often through pre-arranged plans to avoid accusations of trading on material non-public information.

Stakeholder Impact

• Shareholders: Minimal direct impact. The transaction is a routine insider compensation event and not indicative of a change in company fundamentals. The sale under a 10b5-1 plan reduces concerns about opportunistic selling.

Key Dates

Recommendation

The filing reports a routine insider transaction (option exercise and sale under a 10b5-1 plan) and does not provide new fundamental information about Mirum Pharmaceuticals, Inc. that would warrant a change in investment thesis. Therefore, a 'hold' recommendation is appropriate as there is no new data to alter existing positions.

Keywords

Mirum Pharmaceuticals, MIRM, Insider Trading, Form 4, Stock Option Exercise, 10b5-1 Plan, Director Transaction, Equity Sales