7. Stockholders’ Equity

Stock-based Compensation

As of September 30, 2017, we maintained two share based employee compensation plans: the 2012 Incentive Award Plan (“2012 Plan”) and the Amended and Restated 2006 Equity Participation Plan (“2006 Plan”). Upon stockholder approval of the 2012 Plan, we ceased to make grants under the 2006 Plan. In addition, pursuant to the acquisition of AS&E, we assumed two share based employee compensation plans: the AS&E 2005 Equity and Incentive Plan (“2005 AS&E Plan”) and the AS&E 2014 Equity and Incentive Plan (“2014 AS&E Plan”). No new RSU grants will be made under the 2005 AS&E Plan or the 2014 AS&E Plan. The 2012 Plan, the 2006 Plan, the 2005 AS&E Plan and the 2014 AS&E Plan are collectively referred to as the “OSI Plans”.

We recorded stock based compensation expense in the consolidated statement of operations as follows (in thousands):

	Three Months Ended September 30,
	2016		2017
Cost of goods sold	$	295	$	241
Selling, general and administrative	5,060		5,111
Research and development	55		135

Stock based compensation expense	5,410		5,487

As of September 30, 2017, total unrecognized compensation cost related to share based compensation grants were estimated at $0.6 million for stock options and $29.7 million for RSUs under the OSI Plans. We expect to recognize these costs over a weighted average period of 1.9 years with respect to the stock options and 1.8 years for grants of RSUs.

The following summarizes stock option activity during the three months ended September 30, 2017:

			Weighted Average		Weighted-Average	Aggregate
	Number of		Exercise		Remaining Contractual	Intrinsic Value
	Options		Price		Term	(in thousands)
Outstanding at June 30, 2017	780,671		$	30.00
Granted	6,492		$	79.23
Exercised	(80,101	)	$	21.93
Expired or forfeited	(750	)	$	53.28

Outstanding at September 30, 2017	706,312		$	31.34	3.4 years	$	42,401

Exercisable at September 30, 2017	670,471		$	29.02	3.1 years	$	41,802

The following summarizes RSU award activity during the three months ended September 30, 2017:

			Weighted-
			Average
	Shares		Fair Value
Nonvested at June 30, 2017	611,687		$	65.85
Granted	320,837		$	72.98
Vested	(372,248	)	$	65.49
Forfeited	(10,051	)	$	67.86

Nonvested at September 30, 2017	550,225		$	70.22

As of September 30, 2017, there were approximately 0.7 million shares available for grant under the 2012 Plan. Under the terms of the 2012 Plan, RSUs and restricted stock granted from the pool of shares available for grant reduce the pool by 1.87 shares for each award granted. RSUs and restricted stock forfeited and returned to the pool of shares available for grant increase the pool by 1.87 shares for each award forfeited.

We granted 155,488 and 117,346 performance-based RSUs during the three months ended September 30, 2016 and 2017, respectively. These performance-based RSUs are contingent on the achievement of certain performance metrics. The payout can range from zero to 250% of the original number of shares or units awarded.

Share Repurchase Program

In April 2016, the Board of Directors authorized a stock repurchase program of up to 1.0 million shares. During the three months ended September 30, 2017, no shares were repurchased under this program, which leaves available 872,481 shares under this program. This program does not automatically expire unless the Board acts to terminate the program. Upon repurchase, the shares are restored to the status of authorized but unissued, and we record them as a reduction in the number of shares of common stock issued and outstanding in the consolidated financial statements.