Share-Based Compensation

Share-based Compensation

We utilize share-based compensation in the form of stock options, restricted stock, and restricted stock units. The following table summarizes the components of share-based compensation expense for the three months ended March 31, 2018 and 2017 (in thousands):



	Three Months Ended March 31,
	2018		2017
Research and development	$	40	$	46
General and administrative	106		350
Discontinued operations	—		137
Total share-based compensation expense	$	146	$	533

The approval of the 2017 Hitachi Transaction (see Note 3) by our stockholders resulted in a change in control under our equity compensation plans (as defined in the 2009 Plan and the 2015 Equity Plan). Accordingly, all outstanding unvested equity awards were accelerated upon the closing date of the 2017 Hitachi Transaction, resulting in an acceleration of $1.9 million of equity compensation in the second quarter of 2017. In addition, in connection with the 2017 Hitachi Transaction, the Company agreed to extend the post-termination option exercise period for all PCT employees transitioning to Hitachi from 90 days to the earlier of (i) two years (May 18, 2019) or (ii) the date of the employees' termination from PCT. The post-termination option exercise period modification resulted in an additional expense of $0.3 million, which was recorded entirely during the three months ended June 30, 2017 and recorded in discontinued operations, since there were no future service requirements to receive the extended benefit.

Total compensation cost related to nonvested awards not yet recognized and the weighted-average periods over which the awards are expected to be recognized at March 31, 2018 were as follows (in thousands):



	Stock Options		Restricted Stock
Unrecognized compensation cost	$	275.1	$	—
Expected weighted-average period in years of compensation cost to be recognized	2.41		0.00

Total fair value of shares vested and the weighted average estimated fair values of shares granted for the three months ended March 31, 2018 and 2017 were as follows (in thousands):



	Stock Options
	Three Months Ended March 31,
	2018		2017
Total fair value of shares vested	$	82.4	$	507.1
Weighted average estimated fair value of shares granted	$	2.41	$	2.34

Valuation Assumptions

The fair value of stock options and warrants at the date of grant was estimated using the Black-Scholes option pricing model. The expected volatility is based upon historical volatility of the Company’s stock. The expected term for the options is based upon observation of actual time elapsed between date of grant and exercise of options for all employees. The expected term for the warrants is based upon the contractual term of the warrants.