The Company recorded stock-based compensation expense in the condensed consolidated statement of operations for the periods presented as follows (in thousands):


	Three Months Ended March 31,
	2025		2024
Cost of revenue	$	2,481	$	2,033
Research and development	14,106		16,888
Selling, general and administrative	14,489		17,208
Total stock-based compensation expense	$	31,076	$	36,129

Restricted stock units (“RSUs”) activity for the three months ended March 31, 2025 is as follows:


	Restricted Stock Units	Weighted-Average Grant Date Fair Value (per share)
Outstanding as of December 31, 2024	6,493,387	$	35.55
Granted	2,016,004	12.11
Vested	(564,701)	47.42
Cancelled	(320,043)	38.48
Outstanding as of March 31, 2025	7,624,647	$	28.35


	Stock Options	Weighted-Average Exercise Price
Outstanding as of December 31, 2024	4,594,582	$	45.37

Exercised	(277,212)	1.52
Cancelled and forfeited	(96,812)	52.35
Outstanding as of March 31, 2025	4,220,558	$	48.09

In March 2025, the Company granted 561,603 performance stock units (“PSUs”) under the 2019 Plan to certain members of management which are subject to the achievement of certain performance conditions established by the Company’s Compensation Committee of the Board of Directors as described below:

i.50% of target PSUs earned will be based on the Company’s compound annual growth rate (“CAGR”) of the Company’s Revenue over a two-year performance period from January 1, 2025 to December 31, 2026. Holders may earn from 0% to 200% of the target amount of shares and earned PSUs will then be subject to service-based vesting; and

ii.50% of target PSUs earned will be based on the relative Total Shareholder Return (“TSR”) of the Company’s common stock as compared to the TSR of the members of the Russell 3000 Medical Equipment and Services Sector Index over a three-year performance period from January 1, 2025 to December 31, 2027. Depending on the results relative to the TSR market condition, the holders may earn from 0% to 200% of the target amount of shares which will vest at the end of the performance period.

The PSUs will be forfeited if the performance conditions are not achieved at the end of the relative performance periods as described above. The vesting of the PSUs can also be triggered upon certain change in control events or in the event of death or disability.

The weighted-average grant date fair values of the PSUs relating to CAGR and TSR components were $10.76 and $13.94 per share, respectively. Stock-based compensation expense recognized for these awards was approximately $0.1 million for the three months ended March 31, 2025.

The Company estimated the fair values of shares granted under the market-based TSR PSUs using a Monte Carlo simulation model with the following assumptions:

In March 2024, the Company granted 219,168 PSUs under the 2019 Plan to certain members of management, which are subject to the achievement of certain market-condition and performance-condition goals established by the Company’s Compensation Committee of the Board of Directors.

As of March 31, 2025, the measurement periods for the 2025 and 2024 PSUs were not completed and the market and performance criteria for the stock awards was not met and therefore no shares vested or became exercisable.

A total of 4,909,589 shares of Class A common stock were reserved for issuance under the 2019 Employee Stock Purchase Plan (“ESPP”). The price at which Class A common stock is purchased under the ESPP is equal to 85% of the fair market value of the common stock on the first day of the offering period or purchase date, whichever is lower.

During the three months ended March 31, 2025 and 2024, no shares of Class A common stock were issued under the ESPP. As of March 31, 2025, there were 3,928,014 shares available for issuance under the ESPP.