NOTE 13. EMPLOYEE EQUITY-BASED COMPENSATION

The following table summarizes option activity under all plans during the six-month period ended June 30, 2018:



	Number of Shares		Weighted Average Exercise Price per Share
Options Outstanding January 1, 2018	7,328,131		$	10.16
Granted	1,115,371		25.45
Forfeited	(91,043	)	20.97
Exercised	(253,621	)	10.87
Expired	(5,495	)	23.43
Options Outstanding June 30, 2018	8,093,343		12.11

The table below summarizes the resulting weighted average inputs used to calculate the estimated fair value of options awarded during the periods shown below:



	Three Months Ended
	June 30,			June 30,
	2018			2017
Expected term (in years)	6.06			6.12
Volatility	64		%	75		%
Expected dividends	—			—
Risk free interest rates	2.82		%	2.02		%
Weighted average fair value	$	13.53		$	16.80

The following table shows summary information for outstanding options and options that are exercisable (vested) as of June 30, 2018:



	Options Outstanding		Options Exercisable
Number of options	8,093,343		5,689,985
Weighted average remaining contractual term (in years)	6.18		5.13
Weighted average exercise price	$	12.11	$	8.00
Weighted average fair value	$	8.52	$	5.68
Aggregate intrinsic value (in thousands)	$	88,348	$	83,067

The following table summarizes restricted stock unit and restricted stock award activity during the six-month period ending June 30, 2018:



	Number of Shares		Weighted Average Grant Date Fair Value per Share
Outstanding January 1, 2018	24,150		$	26.45
Granted	—		—
Forfeited	—		—
Vested/released	(8,050	)	26.45
Outstanding June 30, 2018	16,100		26.45

Equity-based compensation is summarized below (in thousands):



	Three Months Ended				Six Months Ended
	June 30,		June 30,		June 30,		June 30,
	2018		2017		2018		2017
Cost of sales	$	58	$	22	$	104	$	22
Research and development	838		1,166		2,450		1,892
Sales, general and administrative	2,513		3,047		6,457		5,536
Equity-based compensation expense	$	3,409	$	4,235	$	9,011	$	7,450

As of June 30, 2018 and 2017, $420,000 and $183,000 of equity-based compensation expense was included as a component of capitalized inventory, respectively. As of June 30, 2018 and 2017, $77,000 and $27,000 of equity-based compensation expense was included as a component of capitalized property and equipment, respectively.

As of June 30, 2018, unrecognized equity-based compensation expense related to unvested stock options and unvested restricted stock units was $22.8 million and $111,000, respectively. This is expected to be recognized over the years 2018 through 2023.