Stockholders' Equity

6 Months Ended

Jun. 30, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

10.	Stockholders’ Equity

Stock Options

During the six months ended June 30, 2020, the Company had the following activities under its equity incentive plans:

		Available for Grant			Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value
Balance at December 31, 2019			2,192,545			9,287,901		$	9.44
	Shares authorized		2,000,000			-
	Granted ⁽¹⁾		(1,105,278	)		859,918			48.67
	Exercised ⁽²⁾		92,459			(2,399,296	)		10.00
	Forfeited and expired		21,244			(21,244	)		13.78
Outstanding at June 30, 2020			3,200,970			7,727,279		$	13.62		7.00	$	339,650,595
Vested and expected to vest, net of estimated forfeiture at June 30, 2020						7,418,771		$	13.16		6.92	$	329,498,001
Exercisable at June 30, 2020						4,412,289		$	8.26		5.69	$	217,441,295

(1)	The difference between shares granted in the number of shares available for grant and outstanding options represents the RSUs and RSAs granted for the period.

(2)	Shares presented as available for grant represents shares repurchased for tax withholding upon vesting of RSUs.

Restricted Stock

During the six months ended June 30, 2020, the activity for restricted stock is summarized as follows:

	Shares			Weighted Average Grant-Date Fair Value
Balance at December 31, 2019		399,823		$	10.54
Granted		245,360			48.08
Vested		(230,986	)		9.98
Canceled		-			-
Unvested at June 30, 2020		414,197		$	33.10

Stock-based Compensation

Total stock-based compensation expense was $5.4 million and $10.0 million during the three and six months ended June 30, 2020, respectively, and $2.9 million and $5.6 million during the same respective periods ended June 30, 2019. As of June 30, 2020, $38.0 million, $9.0 million and $321,000 of total unrecognized compensation expenses associated with outstanding employee stock options, unvested restricted stock, and the ESPP, net of estimated forfeitures, respectively, were expected to be recognized over a weighted-average period of 2.52, 1.89 and 0.38 years, respectively.

Equity Follow-On Offering

In June 2020, the Company completed an equity follow-on offering of 5,980,000 shares of its common stock at a sale price of $58.00 per share. The Company received net proceeds of $325.7 million, after deducting underwriting discounts, commissions and offering expenses.