Stock Option Plans

9 Months Ended

Sep. 30, 2017

11.	Stock Option Plans

BioTime adopted the 2012 Equity Incentive Plan, as amended (the "2012 Plan"), under which a maximum of 16,000,000 BioTime common shares are available for the grant of stock options, restricted stock, restricted stock units and stock appreciation rights.

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
Increase to the 2012 Plan option pool		6,000			-			-			-
Options granted		(1,762	)		1,762			-			3.11
Options exercised		-			(9	)		-			2.66
Restricted stock units vested		-			-			(31	)		-
Options forfeited/cancelled		426			(606	)		-			3.99
September 30, 2017 ⁽¹⁾		7,558			8,105			69		$	3.47
Options exercisable at September 30, 2017					4,072					$	3.71

⁽¹⁾ On October 13, 2017, BioTime’s Board of Directors (the “Board”) 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.

Stock-Based Compensation Expense

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

	Nine Months Ended September 30,
	2017			2016
Expected life (in years)		5.47			4.97
Risk-free interest rates		1.78	%		1.43	%
Volatility		59.04	%		60.77	%
Dividend yield		-	%		-	%

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

	Three Months Ended September 30,				Nine Months Ended September 30,
		2017	2016		2017		2016
Research and development	$	326	$	237	$	822	$	2,022
General and administrative		647		473		2,081		4,281
Total stock-based compensation expense	$	973	$	710	$	2,903	$	6,303