In March 2021, the Company closed a follow-on public offering in which it issued and sold approximately 2.5 million shares of common stock (including approximately 0.3 million shares sold pursuant to the full exercise of the underwriters option to purchase additional shares) at an offering price of $34.00 per share, resulting in aggregate net proceeds to the Company of approximately $82.4 million after deducting underwriting discounts, commissions and offering costs.

Restricted stock award (RSA) and restricted stock unit (RSU) activity under our equity incentive plan was as follows (in thousands, except weighted-average grant date fair values):


		Number of Restricted Stock Awards	Weighted-Average Grant Date Fair Value
RSAs at December 31, 2020		653	$	21.30
	Awards granted	—	—
	Awards vested	—	—

RSAs at March 31, 2021		653	$	21.30


		Number of Restricted Stock Units	Weighted-Average Grant Date Fair Value
RSUs at December 31, 2020		2,800	$	20.54
	Awards granted	76	38.76
	Awards vested	(3)	18.63
	Awards forfeited	(7)	24.88
RSUs at March 31, 2021		2,866	$	21.01

The total fair value of RSAs and RSUs vested during the three months ended March 31, 2021 was less than $0.1 million in total. Awards outstanding as of March 31, 2021 include 0.7 million performance-based awards that will vest upon meeting certain performance criteria.

The following table summarizes the Company’s stock option activity during the three months ended March 31, 2021 (in thousands, except weighted-average exercise prices):


	Number of Options	Weighted-Average Exercise Price	Weighted-Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value
Outstanding, December 31, 2020	3,358	$1.53	5.3	$104,510

Options exercised	(452)	$1.27
Options canceled	(2)	$4.79
Outstanding, March 31, 2021	2,904	$1.56	5.1	$89,554
Options exercisable at March 31, 2021	2,408	$1.15	4.8	$75,265
Options vested as of March 31, 2021 and expected to vest after March 31, 2021	2,904	$1.56	5.1	$89,554

Total intrinsic value of options exercised for the three months ended March 31, 2021 and 2020 was $15.0 million and $6.0 million, respectively. The Company received proceeds of $0.6 million from the exercise of options for each of the three months ended March 31, 2021 and 2020.

There were no purchases under the Company's employee stock purchase plan during the three months ended March 31, 2021.

Total stock-based compensation expense was included in our consolidated statements of operations as follows (in thousands):


	Three Months Ended March 31,
		2021		2020
Cost of revenues		$	491	$	345
Research and development		2,918		1,782
Sales, general and administrative		4,645		1,636
		$	8,054	$	3,763

As of March 31, 2021, total unrecognized stock-based compensation related to unvested stock awards was $58.3 million, which will be recognized over the next five years as follows (in thousands):

Total unrecognized stock-based compensation includes approximately 0.3 million awards that do not have a measurement date and have been valued as of March 31, 2021.

On November 14, 2019, the Company's Board of Directors authorized the repurchase of up to $10.0 million of its outstanding shares of common stock. As of March 31, 2021, no repurchases had been executed under the program.