Stock Option Plans (Tables)

3 Months Ended

Mar. 31, 2017

Stock Option Plans [Abstract]

Summary of stock option activity

A summary of BioTime’s 2012 Plan activity and related information follows (in thousands, except per share amounts):

	Shares Available for Grant			Number of Options Outstanding			Number of RSUs Outstanding		Weighted Average Exercise Price of Options
December 31, 2016		2,894			6,958			100	$	3.60
Options granted		(583	)		583			-		3.06
Options exercised		-			(9	)		-		2.66
Options forfeited/cancelled		281			(336	)		-		3.90
March 31, 2017		2,592			7,196			100	$	3.55

Schedule of weighted average assumptions to calculate fair value of stock options

The fair value of each option award is estimated on the date of grant using a Black-Scholes option valuation model applying the weighted-average assumptions noted in the following table:

	Three Months Ended March 31, (unaudited)
	2017			2016
Expected life (in years)		6.08			6.08
Risk-free interest rates		2.07	%		1.60	%
Volatility		59.83	%		62.05	%
Dividend yield		-	%		-	%

Schedule of share-based compensation, employee stock purchase plan, activity

Operating expenses include stock-based compensation expense as follows (in thousands):

		Three Months Ended March 31, (unaudited)
		2017		2016
Research and development	$	331	$	1,206
General and administrative		695		2,167
Total stock-based compensation expense	$	1,026	$	3,373