Quarterly report pursuant to Section 13 or 15(d)

Stock Plans

Stock Plans

6 Months Ended

Jun. 30, 2020

2. Stock Plans

The following table summarizes the stock-based compensation expense recorded for awards under our stock option plans: (in thousands)


	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2020		2019		2020		2019
Research and development	$	—	$	14	$	—	$	91
Selling, general and administrative		79		336		(5)		395
Total stock-based compensation	$	79	$	350	$	(5)	$	486

We use the Black-Scholes-Merton option-pricing model with the following assumptions to estimate the fair value of our stock options:


	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2020		2019		2020		2019
Weighted-average risk-free interest rate	0.4	%	2.1	%	0.4	%	2.2	%
Expected dividend payments	—		—		—		—
Expected holding period (years) 1	5.8		5.9		5.8		5.4
Weighted-average volatility factor 2	1.04		0.93		1.04		0.94
Estimated forfeiture rates for options granted 3	28	%	21	%	28	%	21	%

(1)

Expected holding period is based on historical experience of similar awards, giving consideration to the contractual terms of the stock-based awards, vesting schedules and the expectations of future employee behavior.

(2)

Weighted average volatility is based on the historical volatility of our common stock.

(3)

Estimated forfeiture rates are based on historical data.

The following table summarizes option activity:


				Weighted
		Weighted		Average
		Average		Remaining	Aggregate
		Exercise		Option	Intrinsic
	Options (in	Price per		Term (in	Value (in
(in thousands)	thousands)	share		years)	thousands)
Outstanding December 31, 2019	1,192	$	6.23	7.9	$	—
Granted	50		0.28
Forfeited or expired	(324)		1.88
Outstanding at June 30, 2020	918		7.44	7.0		1
Exercisable at June 30, 2020	824		8.19	6.8		—

Options to purchase 50,000 common shares were granted during the three month periods ended June 30, 2020.

As of June 30, 2020, there was approximately $39,000 of total unrecognized compensation expense related to non-vested stock options. This expense is expected to be recognized over a weighted-average period of approximately 1.8 years.