Our 2018 Equity Incentive Plan (the “2018 EIP”) is intended to be the successor to and continuation of the Dynavax Technologies Corporation 2011 Equity Incentive Plan (the “2011 EIP”). The aggregate number of shares of our common stock that may be issued under the 2018 EIP (subject to adjustment for certain changes in capitalization) is comprised of the sum of (i) 5,000,000 newly reserved shares of common stock, (ii) 140,250 unallocated shares of common stock remaining available for grant under the 2011 EIP as of May 31, 2018, and (iii) 7,477,619 shares subject to outstanding stock awards granted under the 2011 EIP and the Dynavax Technologies Corporation 2017 Inducement Award Plan that may become available from time to time as set forth in the 2018 EIP. The 2018 EIP provides for the issuance of up to 12,617,869 shares of our common stock to our employees and directors.

On May 30, 2019, our stockholders approved an amendment to 2018 Equity Incentive Plan (the “Amended 2018 EIP”) to, among other things, increase the aggregate number of shares of common stock authorized for issuance by 2,300,000. Under the Amended 2018 EIP, the aggregate number of shares of our common stock that may be issued to employees and directors (subject to adjustment for certain changes in capitalization) is 14,917,869.

The Amended 2018 EIP is administered by our Board of Directors, or a designated committee of the Board of Directors, and awards granted under the Amended 2018 EIP have a term of 7 years unless earlier terminated by the Board of Directors. As of December 31, 2019, there were 3,308,216 shares of common stock reserved for issuance under the Amended 2018 EIP.

	Shares Underlying Outstanding Options (in thousands)			Weighted-Average Exercise Price Per Share		Weighted-Average Remaining Contractual Term (years)		Aggregate Intrinsic Value (in thousands)
Balance at December 31, 2018		5,750		$	18.20
Options granted		3,747			6.88
Options exercised		(10	)		5.75
Options cancelled:
Options forfeited (unvested)		(1,278	)		12.54
Options expired (vested)		(203	)		16.52
Balance at December 31, 2019		8,006		$	13.86		4.47	$	2,125
Vested and expected to vest at December 31, 2019		7,729		$	14.11		4.40	$	1,954
Exercisable at December 31, 2019		4,531		$	18.37		3.09	$	3

The total intrinsic value of stock options exercised during the years ended December 31, 2019, 2018 and 2017 was $26,000, $0.2 million and $0.9 million, respectively. The total intrinsic value of exercised stock options is calculated based on the difference between the exercise price and the quoted market price of our common stock as of the close of the exercise date.

The total fair value of stock options vested during the years ended December 31, 2019, 2018 and 2017 was $19.5 million, $8.1 million and $13.0 million, respectively.

Our non-vested stock awards are comprised of restricted stock units granted with performance and time-based vesting criteria. A summary of the status of non-vested restricted stock units as of December 31, 2019, and activities during 2019 are summarized as follows:

	Number of Shares (In thousands)			Weighted-Average Grant-Date Fair Value
Non-vested as of December 31, 2018		1,594		$	8.82
Granted		1,823			8.80
Vested		(970	)		6.79
Forfeited		(663	)		10.81
Non-vested as of December 31, 2019		1,784		$	9.16

Stock-based compensation expense related to restricted stock units was approximately $9.1 million for the year ended December 31, 2019. The aggregate intrinsic value of the restricted stock units outstanding as of December 31, 2019, based on our stock price on that date, was $10.2 million.

The total fair value of restricted stock units vested during the years ended December 31, 2019, 2018 and 2017 was $7.9 million, $19.4 million and $1.2 million, respectively.

Under our stock-based compensation plans, option awards generally vest over a three-year or four-year period contingent upon continuous service and unless exercised, expire seven or ten years from the date of grant (or earlier upon termination of continuous service). The Company has also granted performance-based equity awards to certain of our employees. As of December 31, 2019, approximately 155,000 shares underlying stock options and approximately 89,000 restricted stock unit awards with performance-based vesting criteria were outstanding. All of the awards with performance-based vesting criteria were deemed probable as of December 31, 2019. We recognized stock-based compensation expense for awards with performance-based vesting criteria during the years ended December 31, 2019, 2018 and 2017 of $0.5 million, $1.9 million and $0.3 million, respectively.

The fair value of each option is estimated on the date of grant using the Black-Scholes option valuation model and the following weighted-average assumptions:

	Stock Options									Employee Stock Purchase Plan
	Year Ended December 31,									Year Ended December 31,
	2019			2018			2017			2019			2018			2017
Weighted-average fair value	$	4.58		$	10.75		$	8.27		$	2.72		$	8.30		$	3.05
Risk-free interest rate		2.1	%		2.5	%		1.9	%		1.9	%		2.4	%		1.0	%
Expected life (in years)		4.5			4.2			4.5			1.2			1.3			1.2
Expected Volatility		0.9			0.8			0.9			0.7			1.1			1.0

Expected volatility is based on historical volatility of our stock price. The expected life of options granted is estimated based on historical option exercise and employee termination data. Our senior management, who hold a majority of the options outstanding, and other employees were grouped and considered separately for valuation purposes. The risk-free rate for periods within the contractual life of the option is based on the U.S. Treasury yield curve in effect at the time of grant. Forfeiture estimates are based on historical employee turnover. The dividend yield is zero percent for all years and is based on our history and expectation of dividend payouts.

Compensation expense is based on awards ultimately expected to vest and reflects estimated forfeitures. For equity awards with time-based vesting, the fair value is amortized to expense on a straight-line basis over the vesting periods. For equity awards with performance-based vesting criteria, the fair value is amortized to expense when the achievement of the vesting criteria becomes probable. Stock-based compensation cost for the year ended December 31, 2019 includes incremental cost of $4.1 million for accelerated vesting of stock awards and extension of exercise period of stock options in connection with the retirement of our Chief Executive Officer. See Note 17.

We recognized the following amounts of stock-based compensation expense (in thousands):

	Year Ended December 31,
	2019		2018		2017
Employees and directors stock-based compensation expense	$	25,456	$	23,478	$	14,917

	Year Ended December 31,
	2019		2018		2017
Research and development	$	8,058	$	9,604	$	7,827
Selling, general and administrative		10,224		11,761		7,090
Cost of sales - product		1,088		1,354		-
Inventory		1,964		759		-
Restructuring		4,122		-		-
Total	$	25,456	$	23,478	$	14,917

As of December 31, 2019, the total unrecognized compensation cost related to non-vested stock options and awards deemed probable of vesting, including all stock options with time-based vesting, net of estimated forfeitures, amounted to $28.0 million, which is expected to be recognized over the remaining weighted-average vesting period of 1.7 years. Additionally, as of December 31, 2019, the total unrecognized compensation cost related to equity awards with performance-based vesting criteria amounted to $0.1 million.

The Amended and Restated 2014 Employee Stock Purchase Plan (the “Purchase Plan”) provides for the purchase of common stock by eligible employees and became effective on May 28, 2014. On May 31, 2018, our stockholders approved an amendment to the Purchase Plan to increase the aggregate number of shares of common stock authorized for issuance by 600,000 shares. The purchase price per share is the lesser of (i) 85% of the fair market value of the common stock on the commencement of the two-year offer period (generally, the sixteenth day in February or August) or (ii) 85% of the fair market value of the common stock on the exercise date, which is the last day of a purchase period (generally, the fifteenth day in February or August). For the year ended December 31, 2019, employees have acquired 122,117 shares of our common stock under the Purchase Plan and 450,917 shares of our common stock remained available for future purchases under the Purchase Plan.

As of December 31, 2019, the total unrecognized compensation cost related to shares of our common stock under the Purchase Plan amounted to $0.4 million, which is expected to be recognized over the remaining weighted-average vesting period of 1.4 years.