Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2017

A summary of OncoCyte stock option activity under the Plan and related information follows (in thousands except weighted average exercise price):

Options	Shares Available for Grant			Number of Options Outstanding			Weighted Average Exercise Price
Total at January 1, 2016		1,757			2,240		$	2.03
Options granted		(962	)		962			3.58
Options exercised		-			(100	)		2.19
Options forfeited, cancelled or expired		85			(85	)		2.00
Total at December 31, 2016		880			3,017			2.52
Increase in pool		1,200			-
Options granted		(896	)		896			5.17
Options exercised		-			(323	)		1.89
Options forfeited, cancelled or expired		200			(200	)		3.11
Total at December 31, 2017		1,384			3,390		$	3.25
Exercisable at December 31, 2017					1,835		$	2.48

Categories of Stock-based Compensation Expense

OncoCyte recorded stock-based compensation expense in the following categories on the accompanying statements of operations for the years ended December 31, 2017, 2016 and 2015 (in thousands):

	Year Ended December 31,
	2017		2016		2015
Research and development	$	668	$	312	$	456
General and administrative		841		610		1,359
Sales and marketing		121		-		-
Total stock-based compensation expense	$	1,630	$	922	$	1,815

Assumptions used to Calculate Fair Value of Stock Options

The assumptions that were used to calculate the grant date fair value of OncoCyte’s employee and non-employee stock option grants for the years ended December 31, 2017, 2016 and 2015 were as follows.

	Year Ended December 31,
	2017			2016			2015
Expected life (in years)		6.15			6.21			6.83
Risk-free interest rates		2.03	%		1.46	%		1.87	%
Volatility		66.01	%		64.64	%		74.15	%
Dividend yield		-	%		-	%		-	%