Stock-Based Awards

6 Months Ended

Jun. 30, 2019

Share-based Payment Arrangement [Abstract]

Stock-Based Awards

12. Stock-Based Awards

Equity Incentive Plan Awards

BioTime adopted a 2012 Equity Incentive Plan (the “2012 Plan”) for the grant of stock options, restricted stock, restricted stock units and stock appreciation rights. As of June 30, 2019, a maximum of 16,000,000 common shares were available for grant; this amount was increased to 24,000,000 common shares on July 30, 2019 when shareholder approval was obtained.

A summary of BioTime’s 2012 Plan activity and other stock option awards granted outside of the 2012 Plan related information is as follows (in thousands, except per share amounts):

	Shares Available for Grant			Number of Options Outstanding			Number of RSUs Outstanding			Weighted Average Exercise Price
December 31, 2018		1,885			13,867			402		$	2.44
AgeX distribution adjustment		117			(2	)		3			-
Restricted stock units vested		-			-			(135	)		-
Options granted		(2,337	)		2,337			-			1.14
Options exercised		-			-			-			-
Options expired/forfeited/cancelled		1,264			(1,264	)		-			2.09
June 30, 2019		929			14,938			270		$	2.27
Options exercisable at June 30, 2019					9,213					$	2.59

At the effective time of the Asterias Merger, BioTime assumed sponsorship of the Asterias 2013 Equity Incentive Plan (the “Asterias Equity Plan”), with references to Asterias and Asterias common stock therein to be deemed references to BioTime and BioTime common stock. There were 7,309,184 shares available under the Asterias Equity Plan immediately before the closing of the Asterias Merger, which became 5,189,520 shares immediately following the Asterias Merger. The shares available under the Asterias Equity Plan will be for awards granted to those former Asterias employees who continued as BioTime employees upon consummation of the Asterias Merger. A summary of activity under the Asterias Equity Plan from the closing date of the Asterias Merger through June 30, 2019 is as follows (in thousands, except per share amounts):

	Shares Available for Grant			Number of Options Outstanding			Number of RSUs Outstanding		Weighted Average Exercise Price
March 8, 2019		5,190			-			-	$	-
Options granted		(490	)		490			-		1.59
Options exercised		-			-			-		-
Options forfeited		105			(105	)		-		1.63
June 30, 2019		4,805			385			-		1.58
Options exercisable at June 30, 2019					-				$	-

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 noted in the following table:

	Six Months Ended June 30, (unaudited)
	2019			2018
Expected life (in years)		6.06			5.87
Risk-free interest rates		2.5	%		2.6	%
Volatility		60.2	%		56.1	%
Dividend yield		-	%		-	%

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

	Three Months Ended June 30, (unaudited)				Six Months Ended June 30, (unaudited)
	2019		2018		2019		2018
Research and development	$	161	$	188	$	283	$	381
General and administrative		601		915		1,919		1,706
Total stock-based compensation expense	$	762	$	1,103	$	2,202	$	2,087

The expense related to 84,940 shares of Asterias restricted stock unit awards that immediately vested on the closing of the Asterias Merger and converted into the right to receive shares of BioTime common stock based on the Merger Exchange Ratio, resulting in 60,304 shares of BioTime common stock issued on March 8, 2019, which were included in stock-based compensation expense for the six months ended June 30, 2019. The expense was not included as part of the purchase price of the Asterias Merger because these awards were principally attributable to post-combination services.