The Company has several incentive plans under which stock options, restricted stock units (RSUs), restricted stock awards (RSAs), and cash-settled stock appreciation rights (SARs) have been issued, including the Second Amended and Restated 2006 Omnibus Long-Term Incentive Plan, as amended, and a plan and private placement issuances related to the Company’s acquisition of Machinio. As of September 30, 2019, the Company has reserved a total of 16,300,000 shares of its common stock for exercises of stock options, vesting of RSUs, and grants of RSAs under these plans. Vesting of RSUs and grants of RSAs count as 1.5x shares against the plan reserves. As of September 30, 2019, 1,321,256 shares of common stock remained available for use.


	Year Ended September 30,
	2019		2018		2017
Equity-classified awards:
Stock options	$	1,530	$	858	$	869
RSUs & RSAs	4,496		5,454		7,308
Liability-classified awards:
SARs	$	482	$	285	$	(800)
Total stock compensation expense:	$	6,508	$	6,597	$	7,377

The Company’s total liabilities for liability-classified stock compensation awards was $758 thousand and $749 thousand as of September 30, 2019 and 2018, the current portion of which was $707 thousand and $557 thousand, respectively.


	Stock Options	Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (years)	Aggregate Intrinsic Value
Outstanding as of September 30, 2018	2,018,323	$	10.49	5.13	$	1,143
Granted	1,134,316	$	6.32		$	—
Exercised	(132,633)	$	4.44		$	307
Forfeited	(347,728)	$	6.78		$	279
Outstanding as of September 30, 2019	2,672,278	$	9.50	6.19	$	2,502
Vested and expected to vest as of September 30, 2019	2,609,071	$	9.58	6.15	$	2,409
Exercisable as of September 30, 2019	1,270,164	$	12.94	4.37	$	876

Of the 1,402,114 stock options not yet exercisable as of September 30, 2019, 618,488 can become exercisable by satisfying service conditions only, and 783,626 can become exercisable by satisfying service and performance or market conditions.

Stock options containing only service conditions generally vest over periods of one to four years and expire five to ten years from the date of grant. Stock compensation cost is expensed ratably over the entire service period. As of September 30, 2019,


	Year ended September 30
	2019	2018	2017
Dividend yield	—	—	—
Expected volatility	47.8% - 53.7%	50.8% - 58.6%	54.2% - 54.9%
Risk-free interest rate	1.9% - 2.8%	0.5% - 2.7%	1.7% - 2.2%
Expected term	4.2- 7.1 years	3.8 years	3.8 years

The weighted-average grant date fair value of options granted during the year-ended September 30, 2019, 2018 and 2017 was $2.70, $2.04 and $3.58, respectively. The total intrinsic value of options exercised during 2019, 2018 and 2017 was $307 thousand, $30 thousand and $24 thousand, respectively.


	RSU & RSA	Weighted- Average Grant Date Fair Value		Weighted- Average Remaining Contractual Term (years)	Aggregate Fair Value
Outstanding as of September 30, 2018	2,316,865	$	7.19	2.17	$	14,712
Granted	612,728	$	6.70		$	4,103
Exercised	(731,433)	$	6.85		$	4,757
Forfeited	(274,171)	$	7.02		$	1,939
Outstanding as of September 30, 2019	1,923,989	$	7.19	2.09	$	14,237
Expected to vest as of September 30, 2019	1,193,034	$	6.96	2.18	$	8,828

RSUs containing only service conditions vest ratably each year over periods of one to four years. Stock compensation cost is expensed ratably over the entire service period. As of September 30, 2019, there was $2.9 million of unrecognized compensation cost related to RSUs containing only service conditions, which is expected to be recognized over a weighted-average period of 2.5 years.


	SARs	Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (years)	Aggregate Intrinsic Value
Outstanding as of September 30, 2018	934,205	$	7.23	0.78	$	789
Granted	95,000	$	6.11		$	—
Exercised	(181,009)	$	4.57		$	491
Forfeited	(414,614)	$	8.90		$	74
Outstanding as of September 30, 2019	433,582	$	6.49	0.93	$	748
Vested and expected to vest as of September 30, 2019	379,179	$	5.95	0.92	$	748
Exercisable as of September 30, 2019	143,375	$	5.83	0.23	$	316

Of the 290,207 SARs not yet exercisable as of September 30, 2019, 164,088 can become exercisable by satisfying service conditions only, and 126,119 can become exercisable by satisfying service and performance or market conditions.

As of September 30, 2019, there was $0.1 million of unrecognized compensation cost related to SARs containing only service conditions, which is expected to be recognized over a weighted-average period of 3.2 years. The Company made cash payments of $0.5 million, $0.2 million and $0.3 million to settle SARs exercised during the years ended September 30, 2019, 2018 and 2017, respectively.

The fair value of outstanding SARs containing only service conditions is estimated using the Black-Scholes option-pricing model. The range of assumptions used to determine the fair value of outstanding SARs as of September 30, 2019, 2018, and 2017 were as follows:


	Year ended September 30
	2019	2018	2017
Dividend yield	—	—	—
Expected volatility	38.2% - 48.8%	34.9% - 53.6%	38.2% - 48.8%
Risk-free interest rate	1.3% - 1.7%	2.6% - 2.8%	1.3% - 1.6%
Expected term	0.1-3.3 years	0.1-2.0 years	1.0-3.0 years

Stock awards containing performance conditions vest upon the achievement of specified financial targets of the Company or its business units. Vesting is generally measured on the first day of each fiscal quarter over the four-year terms of the awards, starting with the first fiscal quarter after the first anniversary of the grant date, based upon the trailing twelve months performance of the Company or its business units. When it is probable that the performance targets will be achieved, stock compensation expense is recognized ratably over the derived service period. If the Company determines that achievement of the performance targets is no longer probable, the Company no longer records expense and reverses all previously recognized expense. As of September 30, 2019, there was $0.6 million of unrecognized compensation costs related to stock options and RSUs & RSAs, containing performance conditions that are considered probable of being met, which is expected to be recognized over a weighted-average period of 2.2 years.

Stock awards containing market conditions vest upon the achievement of specified increases in the Company’s share price. Vesting is measured the first day of each fiscal quarter over the four-year terms of the award, starting with the first fiscal quarter after the first anniversary of the grant date, based upon the trailing 20-days average of the Company’s share price. Stock compensation cost is expensed on a straight-line basis over the derived service period for each stock price target within the award. The Company accelerates expense when a stock price target is achieved prior to the derived service period. For equity-classified awards, the Company does not reverse expense recognized if the stock price target(s) are not ultimately achieved, but expense is reversed when such situations occur for liability classified awards. As of September 30, 2019, there was $1.2 million of unrecognized compensation costs related to stock options, RSUs and SARs, containing market conditions, which is expected to be recognized over a weighted-average period of 1.7 years.

The fair value of stock options, RSUs and SARs containing market conditions is estimated using Monte Carlo simulations. The range of assumptions used to determine the fair value of these awards during the years ended September 30, 2019 and 2018 were as follows:


	Year ended September 30
	2019	2018	2017
Dividend yield	—	—	—
Expected volatility	45.5% - 55.0%	50.0% - 54.5%	—%
Risk-free interest rate	1.5% - 2.9%	2.0% - 2.5%	—%
Expected holding period (% of remaining term)	25.9% - 100.0%	20.3%	—%

The Board of Directors authorized the Company to repurchase issued and outstanding shares of its common stock under a share repurchase program approved by the Board of Directors. Share repurchases may be made through open market purchases, privately negotiated transactions or otherwise, at times and in such amounts as management deems appropriate. The timing and actual number of shares repurchased will depend on a variety of factors including price, corporate and regulatory requirements and other market conditions. The repurchase program may be discontinued or suspended at any time and will be funded using the Company's available cash. The Company's Board of Directors reviews the share repurchase program periodically, the last such review having occurred in May 2016. The Company did not repurchase shares under this program during the twelve months ended September 30, 2019. As of September 30, 2019, the Company may repurchase an additional $10.1 million of shares under this program.