17. Share-based Payments

Stock Options

The Company granted options to purchase 245,400 and 163,100 shares of common stock during the six months ended September 30, 2018 and 2017, respectively. The cost associated with stock options is estimated using the Black-Scholes option-pricing model. This model requires the input of subjective assumptions including the expected volatility of the underlying stock and the expected holding period of the option. These subjective assumptions are based on both historical and other information. Changes in the values assumed and used in the model can materially affect the estimate of fair value.

The following assumptions were used to derive the weighted average fair value of the stock options granted:

	Six Months Ended September 30,
	2018			2017
Weighted average risk free interest rate		2.82	%		1.90	%
Weighted average expected holding period (years)		5.94			5.82
Weighted average expected volatility		43.98	%		47.36	%
Weighted average expected dividend yield		-			-
Weighted average fair value of options granted	$	8.71		$	12.69

The following is a summary of stock option transactions:

	Number of Shares			Weighted Average Exercise Price
Outstanding at March 31, 2018		1,143,298		$	16.97
Granted		245,400		$	19.02
Exercised		(39,032	)	$	6.24
Forfeited		(9,700	)	$	26.43
Outstanding at September 30, 2018		1,339,966		$	17.59

At September 30, 2018, options to purchase 418,539 shares of common stock were unvested at the weighted average exercise price of $22.66.

At September 30, 2018, there was $3,721,000 of total unrecognized compensation expense related to unvested stock option awards. The compensation expense is expected to be recognized over a weighted average vesting period of approximately 2.1 years.

Restricted Stock Units (“RSUs”)

During the six months ended September 30, 2018 and 2017, the Company granted 78,400 and 60,000 shares of RSUs, respectively, with an estimated grant date fair value of $1,490,000 and $1,644,000, respectively, which was based on the closing market price on the grant date.

The following is a summary of non-vested RSUs:

	Number of Shares			Weighted Average Grant Date Fair Value
Outstanding at March 31, 2018		133,828		$	28.37
Granted		78,400		$	19.00
Vested		(45,966	)	$	28.77
Forfeited		(1,434	)	$	28.37
Outstanding at September 30, 2018		164,828		$	23.80

At September 30, 2018, there was $3,111,000 of unrecognized compensation expense related to these awards, which will be recognized over the remaining vesting period of approximately 2.1 years.