Stock Option Plans (Tables)

12 Months Ended

Dec. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of Stock Based Compensation Expense

The following table summarizes consolidated stock-based compensation expense, including equity awards by privately-held consolidated subsidiaries, related to stock options and other equity awards for the years ended December 31, 2017, 2016, and 2015, which was allocated as follows (in thousands):

	Year Ended December 31,
	2017		2016		2015
Research and development	$	932	$	2,608	$	3,267
General and administrative		3,000		5,343		7,783
Total stock-based compensation expense	$	3,932	$	7,951	$	11,050

Schedule of Weighted Average Assumptions to Calculate Fair Value of Stock Options

The weighted-average estimated fair value of stock options granted under BioTime’s 2002 Plan and 2012 Plan during the years ended December 31, 2017, 2016 and 2015 was $1.65, $1.69 and $2.13 per share respectively, using the Black-Scholes-Merton option pricing model with the following weighted-average assumptions:

	Year Ended December 31,
	2017		2016		2015
Expected life (in years)		5.55		5.83		5.62
Risk-free interest rates		1.83%		1.45%		1.70%
Volatility		58.76%		61.24%		65.82%
Dividend yield		-%		-%		-%

Schedule of Share-based Compensation, Employee Stock Purchase Plan, Activity

A summary of all equity award activity under BioTime’s 2002 Plan and 2012 Plan for the years ended December 31, 2017, 2016 and 2015 is as follows (in thousands except weighted average exercise price):

	Shares Available for Grant		Number of Options Outstanding		Number of RSUs Outstanding		Weighted Average Exercise Price
January 1, 2015		668		3,974		-	$	4.04
Increase in option pool		6,000		-				-
Granted under 2012 Plan		(1,650)		1,650		-		3.72
Exercised		-		(156)		-		4.00
Forfeited/cancelled/expired under 2002 Plan		-		(35)		-		6.72
Forfeited/cancelled/expired under 2012 Plan		239		(239)		-		3.82
December 31, 2015		5,257		5,194		-	$	3.93
Granted under 2012 Plan		(2,315)		2,315		-		3.03
RSUs		(200)		-		100		-
Common stock issued to consultant in lieu of cash		(28)		-		-		-
Common stock issued to employee for bonuses in lieu of cash		(135)		-		-		-
Forfeited/cancelled/expired under 2002 Plan		-		(236)		-		5.17
Forfeited/cancelled/expired under 2012 Plan		315		(315)		-		3.77
December 31, 2016		2,894		6,958		100	$	3.60
Increase to option pool		6,000		-
Temporary restriction by Board on available pool (1)		(5,000)		-
Granted under 2012 Plan		(1,954)		1,954				3.04
Exercised		-		(9)				2.66
Forfeited/cancelled/expired under 2012 Plan		545		(860)				4.43
RSU vesting		-		-		(38)
December 31, 2017		2,485		8,043		62	$	3.38

(1) On October 13, 2017, BioTime’s Board of Directors determined to temporarily set a limit on shares available for grants of share-based awards pursuant to the 2012 Plan. While that limit remains in place, BioTime will not grant share-based awards for more than a total of approximately 2.5 million of the common shares remaining available for awards under the 2012 Plan.

Schedule of Options Outstanding and Exercisable Range of Exercise Prices

Additional information regarding options outstanding under BioTime’s 2002 Plan and 2012 Plan as of December 31, 2017 is as follows (in thousands except exercise prices and weighted average exercise price):

		Options Outstanding			Options Exercisable
Range of Exercise Prices	Number Outstanding	Weighted Average Remaining Contractual Life (years)		Weighted Average Exercise Price	Number Exercisable		Weighted Average Exercise Price
$2.52 - $3.96	6,883	7.23	$	3.24	3,190	$	3.35
$4.02 - $4.95	1,150	3.17	$	4.22	1,048	$	4.22
$5.02 - $8.58	10	0.20	$	32.62	10	$	7.47
$2.52 - $8.58	8,043	6.64	$	3.38	4,248	$	3.57