Share-Based Payments (Tables)

3 Months Ended

Mar. 31, 2017

Stock-based compensation expense by award type was as follows (in thousands):



	Three Months Ended March 31,
	2017		2016
Stock options	$	187	$	435
Restricted stock	51		54
Restricted stock units	3		92
Employee stock purchase plan	3		5
	$	244	$	586

The Company allocated stock-based compensation expense as follows in the consolidated statements of operations and comprehensive loss (in thousands):



	Three Months Ended March 31,
	2017		2016
Research and development expense	$	40	$	221
General and administrative expense	204		365
	$	244	$	586

A summary of the stock option activity is presented below:



	Shares		Weighted-Average Exercise Price
Outstanding at December 31, 2016	2,024,468		$	4.41
Granted	—		—
Exercised	(140,400	)	0.28
Cancelled or forfeited	(166,887	)	9.85
Outstanding at March 31, 2017	1,717,181		$	4.22
Exercisable at March 31, 2017	863,767		$	4.93
Vested and expected to vest at March 31, 2017⁽¹⁾	1,717,181		$	4.22


⁽¹⁾	Represents the number of vested options, plus the number of unvested options expected to vest. The Company adopted ASU 2016-09 as of January 1, 2017 and elected an accounting policy to record forfeitures as they occur.

A summary of the restricted stock is presented below:



	Restricted Stock		Weighted-Average Grant Date Fair Value
Unvested at December 31, 2016	22,150		$	11.43
Vested	(4,430	)	11.43
Unvested at March 31, 2017	17,720		$	11.43

A summary of the restricted stock units is presented below:



	Restricted Stock Units		Weighted-Average Grant Date Fair Value
Unvested at December 31, 2016	3,333		$	4.09
Vested	(3,333	)	4.09
Unvested at March 31, 2017	—		$	—