8. Stock-Based Compensation

The following table summarizes the stock option and award activity for the nine months ended September 30, 2019:


		Options Outstanding
			Weighted-		Weighted-
	Options and		Average		Average
	Awards		Exercise		Remaining	Aggregate
	Available for	Number of	Price Per		Contractual	Intrinsic
	Grant	Options	Share		Life (years)	Value
						(In thousands)
Balance—December 31, 2018	764,145	1,475,299	$	7.60	7.8	$	284
Authorized	512,864
RSUs granted	(165,152)
RSUs cancelled/forfeited	9,000
Options granted	(587,852)	587,852	$	6.70
Options exercised		(10,278)	$	4.70		$	24
Options cancelled/forfeited	136,154	(145,161)	$	8.78
Balance—September 30, 2019	669,159	1,907,712	$	7.25	8.0	$	385
Options exercisable—September 30, 2019		872,161	$	7.03	7.0	$	385

The total grant date fair value of options vested was $557,000 and $510,000 during the three months ended September 30, 2019 and 2018, respectively, and $1.8 million and $1.4 million during the nine months ended September 30, 2019 and 2018, respectively.

The weighted-average grant date fair value of employee options granted was $4.49 and $4.48 per share during the three months ended September 30, 2019 and 2018, respectively, and $4.11 and $4.56 per share during the nine months ended September 30, 2019 and 2018, respectively.

2016 Employee Stock Purchase Plan

In January 2019, there was an increase of 170,955 shares reserved for issuance under the Company’s Employee Stock Purchase Plan (ESPP). The Company had 417,939 shares available for future issuance under the Company’s ESPP as of September 30, 2019. Employees purchased 22,405 shares for $130,000 during the nine months ended September 30, 2019. Employees purchased 20,057 shares for $137,000 during the nine months ended September 30, 2018.

Modification of Stock Awards

In February 2018, the Company modified the terms of 400,000 vested and unvested stock option awards granted to the Chief Executive Officer, by reducing their exercise price from $16.25 per share to $7.64 per share. There was no change to any of the other terms of the option awards. The modification resulted in an incremental value of $600,000 being allocated to the options, of which $63,000 was recognized to expense immediately based on options that were vested at the time of the modification. The remaining incremental value of $537,000 attributable to unvested options will be recognized over the remaining vesting term through September 2021.

Restricted Stock Units

The following table summarizes Restricted Stock Units (RSUs) activity for the nine months ended September 30, 2019:


	RSUs Outstanding
		Weighted-
		Average
	Number of	Grant Date
	Restricted Stock	Fair Value Per
	Units	Share
Balance—December 31, 2018	93,560	$	8.38
Granted	165,152		6.80
Vested	(30,492)		8.40
Cancelled/forfeited	(9,000)		7.86
Balance—September 30, 2019	219,220	$	7.21

The fair value of RSUs is determined on the date of grant based on the market price of the Company’s common stock on that date. As of September 30, 2019, there was $1.2 million of unrecognized stock-based compensation expense related to RSUs to be recognized over a weighted-average period of 2.5 years.

Stock-based Compensation Expense

The Company recognized stock-based compensation expense from awards granted to employees and non-employees under its equity incentive plans and from its ESPP as follows, excluding amounts related to GLOBALFOUNDRIES, Inc. (GF) (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Research and development	$	176	$	132	$	484	$	378
General and administrative		627		504		1,692		1,403
Sales and marketing		92		86		221		283
Total	$	895	$	722	$	2,397	$	2,064

As of September 30, 2019, there was $5.1 million of total unrecognized compensation expense related to unvested options which is expected to be recognized over a weighted-average period of 2.5 years. Compensation cost capitalized within inventory at September 30, 2019 and at December 31, 2018 was not material.