Mirum Pharmaceuticals, Inc.MIRM
Mirum Pharmaceuticals, Inc. Stock Compensation Disclosure
Stock-Based Compensation
Equity Incentive Plans
In November 2018, the Company adopted the 2018 Equity Incentive Plan (the “2018 Plan”), which permits the granting of stock awards and incentive and nonstatutory stock options to employees, directors and consultants of the Company.
In July 2019, the Company’s board of directors and stockholders approved and adopted the 2019 Equity Incentive Plan (the “2019 Plan”). The 2019 Plan became effective on July 17, 2019. Under the 2019 Plan, the Company may grant stock options, stock appreciation rights, restricted stock, restricted stock units and other stock or cash-based awards to individuals who are then employees, officers, directors or consultants of the Company. Shares subject to outstanding awards under the 2018 Plan as of the effective date of the 2019 Plan that are subsequently canceled, forfeited or repurchased by the Company will be added to the shares reserved under the 2019 Plan. In addition, the number of shares of common stock available for issuance under the 2019 Plan will be automatically increased on the first day of each calendar year during the -year term of the 2019 Plan, beginning with January 1, 2020 and ending with January 1, 2029, by an amount equal to 5% of the outstanding number of shares of the Company’s common stock on December 31st of the preceding calendar year or such lesser amount as determined by the Company’s board of directors. As of December 31, 2025, 2,285,219 shares of common stock were available for issuance under the 2019 Plan.
In March 2020, the compensation committee of the Company’s board of directors approved and adopted the 2020 Inducement Plan (the “2020 Inducement Plan”). Under the 2020 Inducement Plan, the Company may grant nonstatutory stock options, stock appreciation rights, restricted stock and restricted stock units to new employees entering into employment with the Company in accordance with Nasdaq Listing Rule 5635(c)(4). Through December 31, 2025, the Company’s board of directors authorized 5,500,000 shares of the Company’s common stock for future issuance. As of December 31, 2025, 1,439,708 shares of common stock were available for issuance under the 2020 Inducement Plan.
Stock Options
The following table summarizes stock option activity during the year ended December 31, 2025 (in thousands, except share and per share data):
| Number of Awards | Weighted- Average Exercise Price | Weighted- Average Remaining Contractual Life (in Years) | Aggregate Intrinsic Value | |||||||||||||||||||||||
| Outstanding as of December 31, 2024 | 10,031,486 | $ | 18.12 | 6.5 | $ | 233,161 | ||||||||||||||||||||
| Granted | 1,859,835 | $ | 49.25 | |||||||||||||||||||||||
| Exercised | (2,658,854) | $ | 13.62 | |||||||||||||||||||||||
| Canceled and forfeited | (273,976) | $ | 34.93 | |||||||||||||||||||||||
| Outstanding as of December 31, 2025 | 8,958,491 | $ | 25.41 | 6.5 | $ | 479,984 | ||||||||||||||||||||
| Vested and exercisable as of December 31, 2025 | 5,747,724 | $ | 17.61 | 5.4 | $ | 352,815 | ||||||||||||||||||||
Intrinsic value is calculated as the difference between the exercise price of the underlying options and the fair value of the common stock at December 31, 2025 or on the date of exercise, for the options that had exercise prices that were lower than the per share fair value of the common stock on the date of exercise. The weighted-average grant date fair value per share of stock options granted during the years ended December 31, 2025, 2024 and 2023 was $32.71, $20.02 and $18.25 per share, respectively. The total intrinsic value of options exercised during the years ended December 31, 2025, 2024 and 2023 was $123.7 million, $23.1 million and $5.7 million, respectively. As of December 31, 2025, the total unrecognized stock-based compensation related to unvested stock option awards granted was $70.3 million, which the Company expects to recognize over a weighted-average period of approximately 2.7 years.
The fair value of each employee and non-employee stock option grant is estimated on the date of grant using the Black-Scholes option-pricing model. Due to the Company’s limited operating history and a lack of company specific historical and implied volatility data, the expected stock price volatility was based upon the weighting of the Company’s historical volatility and the historical volatility of a peer group of publicly traded companies. The historical volatility data was computed using the daily closing prices for the Company’s and its peer companies’ shares during the equivalent period of the calculated expected term of the stock-based awards. Due to the lack of historical exercise history, the expected term of the Company’s stock options for employees has been determined utilizing the “simplified” method for awards. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Expected dividend yield is zero based on the fact that the Company has never paid cash dividends and does not expect to pay any cash dividends in the foreseeable future.
The following assumptions were used to estimate the fair value of stock option awards granted during the following periods:
| Year Ended December 31, | |||||||||||||||||
| 2025 | 2024 | 2023 | |||||||||||||||
| Expected term (in years) | 5.5-6.1 | 5.5-6.1 | 5.3-6.1 | ||||||||||||||
| Expected volatility | 67.82%-71.31% | 71.79%-80.36% | 80.17%-85.24% | ||||||||||||||
| Risk-free interest rate | 3.69%-4.65% | 3.48%-4.62% | 3.35%-4.67% | ||||||||||||||
| Expected dividend yield | — | — | — | ||||||||||||||
Restricted Stock Units
The following table summarizes the activity under the Company’s restricted stock units for the year ended December 31, 2025:
| Number of Awards | Weighted-Average Grant Date Fair Value per Award | |||||||||||||
| Unvested and outstanding as of December 31, 2024 | 1,392,562 | $ | 26.63 | |||||||||||
| Granted | 787,765 | $ | 49.47 | |||||||||||
| Vested | (644,037) | $ | 25.29 | |||||||||||
| Cancelled/Forfeited | (120,371) | $ | 36.84 | |||||||||||
| Unvested and outstanding as of December 31, 2025 | 1,415,919 | $ | 39.08 | |||||||||||
The fair value of restricted stock unit (“RSU”) awards granted to employees and nonemployees is equal to the closing market price of the Company’s common stock on the grant date.
As of December 31, 2025, the total unrecognized stock-based compensation related to restricted stock unit awards granted was $35.6 million, which the Company expects to recognize over a weighted-average period of approximately 1.9 years.
Performance Stock Units
The fair value of performance stock units (“PSUs”) granted to employees is equal to the closing market price of the Company’s common stock on the grant date. PSUs are subject to vest only if certain specified sales-based criteria are achieved and the employees’ continued service with the Company. As of December 31, 2025, certain specified sales-based criteria were deemed probable of achievement or already achieved. Stock-based compensation for PSUs is recognized over the service period beginning in the period the Company determines it is probable that the performance criteria will be achieved. PSUs generally vest over a three-year service period. The number of shares earned is adjusted based on the specified sales-based criteria achievement.
The following table summarizes the activity under the Company’s performance stock units in base units for the year ended December 31, 2025:
| Number of Awards | Weighted-Average Grant Date Fair Value per Award | ||||||||||
| Unvested and outstanding as of December 31, 2024 | 284,955 | $ | 25.15 | ||||||||
| Granted | 217,547 | $ | 40.18 | ||||||||
| Vested | (147,675) | $ | 23.92 | ||||||||
| Cancelled/Forfeited | (1,084) | $ | 25.39 | ||||||||
| Unvested and outstanding as of December 31, 2025 | 353,743 | $ | 34.91 | ||||||||
As of December 31, 2025, the total unrecognized stock-based compensation related to performance stock units granted was $9.0 million, which the Company expects to recognize over a weighted-average period of approximately 1.7 years.
2019 Employee Stock Purchase Plan
In July 2019, the Company’s board of directors and stockholders approved and adopted the 2019 Employee Stock Purchase Plan (“ESPP”). During the year ended December 31, 2025, 106,977 shares were issued under the ESPP. As of December 31, 2025, the Company had 1,759,019 shares available for future issuance under the ESPP.
Stock-Based Compensation Expense
Total stock-based compensation is reflected in the accompanying consolidated statements of operations as follows (in thousands):
| Year Ended December 31, | ||||||||||||||||||||
| 2025 | 2024 | 2023 | ||||||||||||||||||
| Selling, general and administrative | $ | 46,094 | $ | 32,308 | $ | 24,131 | ||||||||||||||
| Research and development | 24,158 | 15,188 | 10,892 | |||||||||||||||||
| Cost of sales | 1,172 | 948 | — | |||||||||||||||||
| Total | $ | 71,424 | $ | 48,444 | $ | 35,023 | ||||||||||||||
Stock-based compensation capitalized into inventory was $0.7 million, $1.1 million and $0.8 million for the years ended December 31, 2025, 2024, 2023, respectively.
About Stock Compensation Disclosures
Stock-based compensation disclosures detail the equity awards granted to employees and executives — including stock options, restricted stock units (RSUs), and performance shares — along with the valuation methods and assumptions used to expense them. This section reveals the true cost of talent retention and the alignment between management incentives and shareholder interests.
Key signals: total unrecognized compensation expense and its expected recognition period signal future earnings headwinds from already-granted awards. For stock options, examine Black-Scholes assumptions — expected volatility, risk-free rate, and expected term — as understating any of these reduces reported compensation expense. Compare stock compensation expense as a percentage of revenue against peers to assess dilution cost. Watch vesting schedules for acceleration clauses tied to change-of-control events. Performance-based awards with undemanding targets may indicate weak governance. Add back stock compensation to operating cash flow to calculate a more conservative free cash flow figure.