We have an equity incentive plan under which we granted stock options and restricted stock units (RSUs), including performance-based restricted stock units (PSUs), to employees and directors. As of September 30, 2024, 24.7 million shares were available for grant under the Exelixis, Inc. 2017 Equity Incentive Plan (as amended and restated, the 2017 Plan). The share reserve is reduced by 1 share for each share issued pursuant to a stock option and 2 shares for full value awards, including RSUs and PSUs.

On May 30, 2024, at the 2024 Annual Meeting of Stockholders, our stockholders approved the amendment and restatement of the Exelixis, Inc. 2000 Employee Stock Purchase Plan (as amended and restated, the Amended ESPP). The amendment and restatement increased the share reserve under the Amended ESPP by 6.0 million shares. As of September 30, 2024, 7.2 million shares were available for grant under the Amended ESPP.


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023

Research and development	$	8,764	$	12,438	$	21,834	$	25,279
Selling, general and administrative	14,259		28,040		45,656		56,760
Total stock-based compensation expense	$	23,023	$	40,478	$	67,490	$	82,039


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
Stock options	$	1,397	$	1,882	$	4,659	$	5,966
Restricted stock units	20,626		18,440		58,224		50,804
Performance stock units	370		19,463		2,194		22,129
Employee stock purchase plan	630		693		2,413		3,140
Total stock-based compensation expense	$	23,023	$	40,478	$	67,490	$	82,039

During the nine months ended September 30, 2024, we granted 0.1 million stock options with a weighted-average exercise price of $22.46 per share and a weighted-average grant date fair value of $9.79 per share. Stock options granted during the nine months ended September 30, 2024 have vesting conditions and contractual lives of a similar nature to those described in “Note 8. Stockholders’ Equity” of the “Notes to Consolidated Financial Statements” included in Part II, Item 8 of our Fiscal 2023 Form 10-K. As of September 30, 2024, there were 6.2 million stock options outstanding and $5.3 million of related unrecognized compensation expense.

In February 2024, we awarded to certain employees an aggregate of 1.3 million RSUs (the target number) that are subject to a total shareholder return (TSR) market condition (the 2024 TSR-based RSUs). The TSR market condition is based on our relative TSR percentile rank compared to companies in the Nasdaq Biotechnology Index during the performance period, which is December 30, 2023 through January 1, 2027. Depending on the results relative to the TSR market condition, the holders of the 2024 TSR-based RSUs may earn up to 175% of the target number of shares. 50% of the shares earned pursuant to the 2024 TSR-based RSU awards will vest shortly after the end of the performance period, and the remainder will vest approximately one year later, subject to an employee’s continuous service. These 2024 TSR-based RSUs will be forfeited if the market condition at or above a threshold level is not achieved at the end of the performance period on January 1, 2027.

The Monte Carlo simulation model assumed correlations of returns of the stock prices of Exelixis common stock and the common stock of a peer group of companies and historical stock price volatility of the peer group of companies. The valuation model also used terms based on the length of the performance period and compound annual growth rate goals for TSR based on the provisions of the awards.

During the nine months ended September 30, 2024, we granted 3.4 million service-based RSUs with a weighted- average grant date fair value of $22.00 per share. As of September 30, 2024, there were 13.5 million RSUs outstanding, including RSUs that are subject to a TSR market condition, and $178.7 million of related unrecognized compensation expense. Service-based RSUs granted to employees during the nine months ended September 30, 2024 have vesting conditions and contractual lives of a similar nature to those described in “Note 8. Stockholders’ Equity” of the “Notes to Consolidated Financial Statements” included in Part II, Item 8 of our Fiscal 2023 Form 10-K.

As of September 30, 2024, there were 2.4 million PSUs outstanding, of which 0.8 million PSUs relate to awards for which we either achieved the performance goal or determined that attainment of the performance goal was probable. Expense recognition for PSUs commences when it is determined that attainment of the performance goal is probable. As of September 30, 2024, the remaining unrecognized stock-based compensation expense for the PSUs that were either achieved or deemed probable of achievement was $1.2 million. The total unrecognized compensation expense for the PSUs for which we have not yet determined that attainment of the performance goal is probable was $35.9 million. For more information about our PSUs, see “Note 8. Stockholders’ Equity” of the “Notes to Consolidated Financial Statements” included in Part II, Item 8 of our Fiscal 2023 Form 10-K.

In January 2024, our Board of Directors authorized a stock repurchase program to acquire up to $450.0 million of our outstanding common stock before the end of 2024. As of June 30, 2024, we completed the repurchase of 20.3 million shares of common stock for an aggregate purchase price of $450.0 million pursuant to our stock repurchase program. In August 2024, our Board of Directors authorized a stock repurchase program to acquire up to $500.0 million of our outstanding common stock before the end of 2025. Under this program, during the third quarter of 2024, we repurchased 0.5 million shares of common stock for an aggregate purchase price of $12.4 million. As of September 30, 2024, approximately $487.6 million remained available for future stock repurchases before the end of 2025.

Stock repurchases under this program may be made from time to time through a variety of methods, which may include open market purchases, in block trades, Rule 10b5-1 trading plans, accelerated share repurchase transactions, exchange transactions, or any combination of such methods. The timing and amount of any stock repurchases under the stock repurchase program will be based on a variety of factors, including ongoing assessments of the capital needs of the business, alternative investment opportunities, the market price of our common stock and general market conditions. The program does not obligate us to acquire any particular amount of our common stock, and the stock repurchase program may be modified, suspended or discontinued at any time without prior notice.