In 2010, the Company adopted the 2010 Equity Incentive Plan and later amended it in 2014, 2017 and 2018 (the “Amended 2010 Plan”). The Amended 2010 Plan was terminated in August 2019. As of December 31, 2019, no new awards may be made under the Amended 2010 Plan, and equity awards for approximately 172,000 shares were outstanding with a weighted-average exercise price of $20.00 per share. The Amended 2010 Plan will remain in effect as to outstanding equity awards granted under the plan prior to the date of expiration.

In August 2019, the Company’s stockholders approved the 2019 Stock Incentive Plan (the “2019 Plan”), and it replaced the Amended 2010 Plan. The 2019 Plan authorizes the board of directors or the compensation committee of the board of directors to grant a broad range of awards including stock options, stock appreciation rights, restricted stock, performance-based awards, and restricted stock units. Under the 2019 Plan, 182,500 shares have been reserved for issuance. The 2019 Plan provides for annual option grants or other awards to the Company’s non-employee directors to acquire up to 2,000 shares and for a one-time grant of an option or other award to a non-employee director to acquire up to 6,000 shares upon his or her initial appointment or election to the board of directors.

Under the 2019 Plan, the term of all incentive stock options granted to a person who, at the time of grant, owns stock representing more than 10% of the voting power of all classes of the Company’s stock may not exceed five years. The exercise price of stock options granted under the 2019 Plan must be at least equal to the fair market value of the shares on the date of grant. Generally, awards under the 2019 Plan will vest over a three to four-year period, and options will have a term of 10 years from the date of grant. In addition, the 2019 Plan provides for automatic acceleration of vesting for options granted to non-employee directors upon a change of control of the Company.

The Amended 2010 Plan and the 2019 Plan are referred to collectively as the “Plans.”

The Company may also award shares to new employees outside the Plans, as material inducements to the acceptance of employment with the Company, as permitted under the Listing Rules of the Nasdaq Stock Market. These awards must be approved by the compensation committee of the board of directors, a majority of the independent directors or, below a specified share level, by an authorized executive officer. As of December 31, 2019 and 2018, no such awards were outstanding.

In June 2010, the Company’s stockholders approved the 2010 Employee Stock Purchase Plan (the “ESPP”) with a total of 200,000 shares of common stock initially reserved for issuance. On September 1, 2010, the Company commenced the first offering period under the ESPP. In May 2015, the Company’s stockholders approved an amendment increasing the number of shares reserved for issuance by 200,000 shares. The ESPP, which is intended to qualify under Section 423 of the IRC, is administered by the board of directors or the compensation committee of the board of directors. The ESPP provides that eligible employees may purchase up to $25,000 worth of the Company’s common stock annually over the course of two six-month offering periods. The purchase price to be paid by participants is 85% of the price per share of the Company’s common stock either at the beginning or the end of each six-month offering period, whichever is less.

In February 2017, the Company’s board of directors canceled the ESPP purchase period that began September 1, 2016 and directed the Company to refund outstanding payroll contributions. As of December 31, 2019, there were approximately 7,500 shares authorized and unissued under the ESPP.

The unamortized compensation cost, as of December 31, 2019 was $0.2 million related to stock options and is expected to be recognized as expense over a weighted average period of approximately 2.2 years. The unamortized compensation cost, as of December 31, 2019 was $0.3 million related to restricted stock units and is expected to be recognized as expense over a weighted average period of approximately 2.1 years. For the year ended December 31, 2019, the fair value of options and awards vested was approximately $0.3 million.

The Company is required to present the tax benefits resulting from tax deductions in excess of the compensation cost recognized from the exercise of stock options as financing cash flows in the consolidated statements of cash flows. For the years ended December 31, 2019, 2018 and 2017, there were no such tax benefits associated with the exercise of stock options.

The fair value of the Company’s share-based payment awards for the years ended December 31, 2018, 2017 and 2016 was estimated on the grant dates using the Black-Scholes valuation option-pricing model with the following assumptions:

The risk-free interest rate was derived from the Daily Treasury Yield Curve Rates as published by the U.S. Department of the Treasury as of the grant date for terms equal to the expected terms of the options. The expected volatility was based on the historical volatility of the Company’s stock price over the expected term of the options. The expected term of options granted was derived from historical data based on employee exercises and post-vesting employment termination behavior. A dividend yield of zero is applied because the Company has never paid dividends and has no intention to pay dividends in the near future.

Prior to January 1, 2019, the stock-based compensation expense recorded is adjusted based on estimated forfeiture rates. An annualized forfeiture rate was used as a best estimate of future forfeitures based on the Company’s historical forfeiture experience. The stock-based compensation expense was adjusted in later periods if the actual forfeiture rate is different from the estimate. Upon the adoption of ASU No. 2016-09 on January 1, 2019, the Company elected to change its accounting policy to account for forfeitures as they occur. Historically, estimated forfeitures were immaterial to the consolidated financial statements

A summary of stock option and restricted stock unit (“RSU”) award activity under the Plans is presented below (in thousands, except exercise price):

				Options outstanding
							Weighted
	Shares						Average
	Available			Number of			Exercise
	for Grant			Shares			Prices
Balance as of January 1, 2017		7			26		$	277.62
Additional shares authorized under the Plan		12			—			—
RSUs granted		(21	)		—			—
RSUs cancelled and returned to the Plan		3			—			—
Options granted		(8	)		8		$	15.15
Options cancelled and returned to the Plan		19			(19	)	$	313.80
Balance as of December 31, 2017		12			15		$	96.24
Additional shares authorized under the Plan		202			—			—
RSUs granted		(13	)		—			—
RSUs cancelled and returned to the Plan		1			—			—
Options granted		(2	)		2		$	25.60
Balance as of December 31, 2018		200			17		$	83.84
Additional shares authorized under the Plan		183			—			—
RSUs granted		(120	)		—			—
RSUs cancelled and returned to the Plan		1			—			—
Options granted		(145	)		145		$	2.64
Options cancelled and returned to the Plan		1			(1	)	$	144.00
Plan termination		(32	)		—		$	—
Balance as of December 31, 2019		88			161		$	10.85

A summary of RSU activity under the Plans is presented below (in thousands, except fair value):

				Weighted
				Average
	Number of			Grant-Date
	Shares			Fair Value
Non-vested shares as of January 1, 2017		7		$	162.55
Granted		21		$	18.60
Vested		(6	)	$	115.24
Cancelled		(3	)	$	100.78
Non-vested shares as of December 31, 2017		19		$	31.59
Granted		13		$	17.26
Vested		(17	)	$	27.24
Cancelled		(1	)	$	24.14
Non-vested shares as of December 31, 2018		14		$	24.31
Granted		120		$	3.79
Vested		(30	)	$	12.89
Cancelled		(1	)	$	25.13
Non-vested shares as of December 31, 2019		103		$	3.75

The total intrinsic value of the RSUs outstanding as of December 31, 2019 was $0.2 million.

The following table summarizes significant ranges of outstanding and exercisable options as of December 31, 2018 (in thousands, except contractual life and exercise price):

	Options Outstanding						Options Exercisable
			Weighted
			Average
			Remaining		Weighted				Weighted
			Contractual		Average				Average		Aggregate
	Number		Life		Exercise		Number		Exercise		Intrinsic
Range of Exercise Price	Outstanding		(in Years)		Price		Exercisable		Price		value
$1.57 - $14.99		144		9.26	$	2.64		21	$	3.70	$	—
$15.00 - $25.59		8		3.74	$	15.00		5	$	15.00	$	—
$25.60 - $143.99		3		4.36	$	41.88		2	$	47.10	$	—
$144.00 - $409.99		5		6.65	$	144.00		5	$	144.00	$	—
$410.00 - $924.00		1		5.19	$	430.64		1	$	430.64	$	—
$1.57 - $924.00		161		8.80	$	10.85		34	$	40.81	$	—
Exercisable		34		7.78	$	40.81

There were no stock options exercised during the years ended December 31, 2019, 2018, or 2017. The intrinsic value of outstanding options as of December 31, 2019 was zero.