v3.23.2
Share-Based Payments
 6 Months Ended
Jun. 30, 2023
Share-Based Payment Arrangement [Abstract]  
Share-Based Payments Share-Based Payments
2023 Stock Incentive Plan and Inducement Grants
In June 2023, our stockholders approved the 2023 Stock Incentive Plan, or the 2023 Plan. The 2023 Plan provides for the grant of incentive stock options, nonstatutory stock options, stock appreciation rights, restricted stock awards, restricted stock units, or RSUs, performance-based share units, or PSUs, and other stock-based awards to employees, advisors, consultants and non-employee directors.
Following the adoption of the 2023 Plan, we ceased granting equity awards under the 2013 Stock Incentive Plan, or the 2013 Plan. Any outstanding equity awards that were previously granted under the 2013 Plan continue to be governed by their terms. Following adoption of the 2013 Plan, we ceased granting equity awards under the 2007 Stock Incentive Plan, or the 2007 Plan. There are no outstanding equity awards under the 2007 Plan.
In connection with the start of employment of our Chief Executive Officer and Chief Financial Officer in 2022, and our Chief Commercial Officer in 2023, our board of directors granted each of them equity awards in the form of stock options, RSUs and
PSUs, which awards were made outside our equity incentive plans as inducements material to their respective entry into employment with us in accordance with Nasdaq Listing Rule 5635(c)(4).
As of June 30, 2023, the maximum number of shares reserved under the 2007 Plan, the 2013 Plan, the 2023 Plan and the inducement grants described above was 11,881,185, and we had 4,265,366 shares available for future issuance under the 2023 Plan.
Stock options
The following table presents stock option activity for the six months ended June 30, 2023:
Number of
Stock Options
Weighted-Average
Exercise Price
Outstanding at December 31, 20225,772,564 $48.81 
Granted853,686 25.84 
Exercised(152,849)9.97 
Forfeited/Expired(684,129)56.55 
Outstanding at June 30, 20235,789,272 $45.53 
Exercisable at June 30, 20233,403,431 $55.74 
Vested and expected to vest at June 30, 20235,789,272 $45.53 
At June 30, 2023, there was approximately $36.7 million of total unrecognized compensation expense related to unvested stock option awards, which we expect to recognize over a weighted-average period of approximately 2.71 years.
Restricted stock units
The following table presents RSU activity for the six months ended June 30, 2023:
Number of
Stock Units
Weighted-Average
Grant Date Fair 
Value
Unvested shares at December 31, 20221,117,921 $38.30 
Granted856,710 25.87 
Vested(395,095)42.52 
Forfeited(164,317)33.28 
Unvested shares at June 30, 20231,415,219 $30.18 
As of June 30, 2023, there was approximately $32.6 million of total unrecognized compensation expense related to RSUs, which we expect to recognize over a weighted-average period of approximately 2 years.
Performance-based stock units
The following table presents PSU activity for the six months ended June 30, 2023:
Number of
Stock Units
Weighted-Average
Grant Date Fair 
Value
Unvested shares at December 31, 2022430,243 $35.87 
Granted125,897 25.23 
Vested(92,257)30.18 
Forfeited(95,250)46.53 
Unvested shares at June 30, 2023368,633 $30.90 
Stock-based compensation expense associated with these PSUs is recognized if the underlying performance condition is considered probable of achievement using our management’s best estimates.
As of June 30, 2023, there was no unrecognized compensation expense related to PSUs with performance-based vesting criteria that are considered probable of achievement, and $11.4 million of total unrecognized compensation expense related to PSUs with performance-based vesting criteria that are considered not probable of achievement.
Market-based stock units
The following table presents market-based stock unit, or MSU, activity for the six months ended June 30, 2023:
Number of
Stock Units		Weighted-Average
Grant Date Fair
Value
Unvested shares at December 31, 202242,695 $41.50 
Granted— — 
Unvested shares at June 30, 202342,695 $41.50 
The fair value of MSUs are estimated using a Monte Carlo simulation model. Assumptions and estimates utilized in the model include the risk-free interest rate, dividend yield, expected stock volatility and the estimated period to achievement of the market condition. As of June 30, 2023, there was no remaining unrecognized compensation expense related to MSUs.
2013 Employee Stock Purchase Plan
In June 2013, our Board of Directors adopted, and in July 2013 our stockholders approved, the 2013 Employee Stock Purchase Plan, or the 2013 ESPP. We issued and sold 54,867 and 48,156 shares of common stock during the six months ended June 30, 2023 and 2022, respectively, under the 2013 ESPP. The 2013 ESPP provides participating employees with the opportunity to purchase up to an aggregate of 2,363,636 shares of our common stock. As of June 30, 2023, we had 1,744,004 shares of common stock available for future issuance under the 2013 ESPP.
Stock-based compensation expense
Stock-based compensation expense by award type included within the condensed consolidated statements of operations is as follows:
Three Months Ended
June 30,		Six Months Ended
June 30,
(In thousands)2023202220232022
Stock options$3,937 $5,655 $8,894 $11,856 
Restricted stock units4,754 5,232 9,701 11,397 
Performance-based stock units2,784 — 2,784 2,919 
Employee stock purchase plan262 278 497 503 
Total stock-based compensation expense$11,737 $11,165 $21,876 $26,675 
Expenses related to stock options and stock-based awards were allocated as follows in the condensed consolidated statements of operations:
Three Months Ended
June 30,		Six Months Ended
June 30,
(In thousands)2023202220232022
Research and development expense$4,540 $4,923 $8,895 $11,579 
Selling, general and administrative expense7,197 6,242 12,981 15,096 
Total stock-based compensation expense$11,737 $11,165 $21,876 $26,675