On February 22, 2021, the Company completed a follow-on public offering, in which it issued and sold 1,500,000 shares of its common stock and MegaChips sold 1,500,000 of the Company’s common stock held by them at a price of $127 per share.

The following table summarizes the restricted stock unit award (“RSU”) and cash restricted stock unit award (“CRSU”), activity for the three months ended March 31, 2021:

	RSU			Grant Date		CRSU			Grant Date
	Number of			Fair Value		Number of			Fair Value
	Shares			per share		Shares			per share
Unvested at December 31, 2020		2,735,706		$	22.4		624		$	35.1
Granted		190,838			107.1		3,025			111.9
Vested		(189,460	)		22.8		(3,405	)		101.7
Forfeited		(13,840	)		13.0		—			—
Unvested at March 31, 2021		2,723,244		$	28.2		244		$	58.4

On August 4, 2020, the Compensation Committee of the Company adopted and approved the Executive Bonus and Retention Plan (the “Bonus and Retention Plan”) with target bonus amounts and performance goals for the second half of the fiscal year 2020 (the “2020 Goals”). In January 2021, the Compensation Committee approved target bonus amounts and performance goals for the first half of the fiscal year 2021 (the “1H2021 Goals”). The 2020 Goals and 1H2021 Goals are based on the achievement of revenue and Non-GAAP operating profit for the second half of 2020 and first half of 2021, respectively, as well as individual performance goals. The target bonuses were granted based on a fixed dollar amount to be settled in RSUs on the vesting date and hence the awards have been classified as liability-based awards. Such expense is included in the non-cash adjustment within stock-based compensation expense on the condensed consolidated cash flow statements. The liability of $0.5 million for 1H2021 Goals was recorded as accrued expenses and other current liabilities in the condensed consolidated balance sheet. Actual payouts for 2020 Goals ranged from 119% to 144% of target, based on performance.

In the three months ended March 31, 2021, the Company granted CRSUs as part of an employee bonus plan. Generally, such units are granted quarterly and fully vest at the end of the quarter they are granted except units granted to new hires that have a one-year cliff vesting. Such awards have also been classified as liability-based awards.

The following table presents the detail of stock-based compensation expense amounts included in the condensed consolidated statement of operations for each of the periods presented:

	Three Months Ended March 31,
	2021		2020
Equity awards	(in thousands)
Cost of revenue	$	384	$	56
Research and development		2,456		942
Selling, general and administrative		3,335		1,757
	$	6,175	$	2,755

Liability-based awards - equity settled
Cost of revenue	$	17	$	—
Research and development		204		—
Selling, general and administrative		264		—
	$	485	$	—
Total stock-based compensation - equity settled	$	6,660	$	2,755

Liability-based awards - cash settled
Cost of revenue	$	102	$	—
Research and development		106		—
Selling, general and administrative		108		—
Total stock-based compensation - cash settled	$	316	$	—
Total stock-based compensation expense	$	6,976	$	2,755

As of March 31, 2021, there was $70.2 million and $0.9 million of unrecognized compensation costs related to RSUs granted and liability-based awards granted, respectively. The unrecognized compensation cost is expected to be recognized over a weighted average period of 3.7 years for equity awards and 0.4 years for liability-based awards.