The Company's 2015 Long-Term Incentive Plan ("2015 Stock Plan") and 2021 Incentive Award Plan (“2021 Stock Plan” and, together, “Stock Plans”) permit the grant of stock options, restricted stock units (“RSUs”), and other stock-based awards to employees, non-employee directors, and consultants. As of March 31, 2022, 99 million and 145 million shares were reserved for issuance under the 2015 Stock Plan and 2021 Stock Plan, respectively. As of March 31, 2022, 31 million shares were reserved for issuance under the 2021 Employee Stock Purchase Plan (“ESPP”).

Because no awards granted under the 2015 Stock Plan vested, were expected to vest, or were exercisable prior to the IPO, the Company recognized no stock-based compensation cost during the three months ended March 31, 2021. The following table summarizes the Company’s stock-based compensation expense for the Stock Plans and ESPP recognized during the three months ended March 31, 2022 by line item in the Condensed Consolidated Statement of Operations (in millions):


	March 31, 2022
Cost of revenues	$	10
Research and development	138
Selling, general, and administrative	169
Total stock-based compensation expense	$	317