Stockholders' Equity and Share-based Compensation

Share Repurchase

In September 2017, the Board of Directors terminated the repurchase program that was previously approved in 2015 and approved a new repurchase program (the “Repurchase Program”), which allows the Company to repurchase its common shares from the open market pursuant to a pre-established Rule 10b5-1 trading plan or through privately negotiated transactions up to an aggregate of $30.0 million. The amount and timing of any repurchases under the Repurchase Program depend on a number of factors, including but not limited to, the trading price, volume, availability of the Company's common shares and the amount of available cash reserve. Shares repurchased under this program are accounted for as treasury shares and the total cost of shares repurchased is recorded as a reduction of shareholders' equity.

During the three months ended September 30, 2018, the Company repurchased an aggregate of 111,509 shares from the open market, for a total cost of $1.5 million, excluding fees and related expenses, at an average price of $13.43 per share. Since the inception of the prior repurchase program in 2010, the Company repurchased an aggregate of 6,784,648 shares from the open market including shares purchased in a dutch tender offer for a total cost of $67.3 million, at an average price of $9.92 per share, excluding fees and related expenses. No repurchased shares have been retired. Of the 6,784,648 repurchased shares, 133,728 shares with a weighted average repurchase price of $10.48 per share, were reissued at an average price of $5.77 per share pursuant to option exercises and vested restricted share units. As of September 30, 2018, approximately $13.4 million remained available under the Repurchase Program.

Time-based Restricted Stock Units ("TRSU")

The following table summarizes the Company's TRSU activities for the three months ended September 30, 2018:



	Number of Restricted Stock Units		Weighted Average Grant Date Fair Value Per Share		Weighted Average Remaining Recognition Period (Years)	Aggregate Intrinsic Value
Nonvested at June 30, 2018	919,023		$	15.14	1.62	$	13,086,888
Granted	39,676		$	14.24
Vested	(35,566	)	$	14.64
Forfeited	(5,375	)	$	11.97
Nonvested at September 30, 2018	917,758		$	15.14	1.46	$	10,673,526
TRSUs vested and expected to vest	839,391				1.39	$	9,762,119

Market-based Restricted Stock Units ("MSU")

During the three months ended September 30, 2018, the Company granted 1.3 million market-based restricted stock units ("MSUs") to its certain personnel. The number of shares to be earned at the end of performance period is determined based on the Company’s achievement of specified stock prices and revenue thresholds during the performance period from January 1, 2019 to December 31, 2021as well as the recipients remaining in continuous service with the Company through such period. The MSU vests in four equal annual installments after the end of performance period. The Company estimated the grant date fair values of its MSU with derived service periods of 4.5 to 7.5 years using a Monte-Carlo simulation model with the following assumptions: Risk-free interest rate of 2.7%, expected term of 3.5 years, expected volatility of 38.8% and dividend yield of 0%. The Company recorded approximately $0.2 million of expenses for these MSUs during the three months ended September 30, 2018.

The following table summarizes the Company's MSU activities for the three months ended September 30, 2018:



	Number of Performance-based Restricted Stock Units	Weighted Average Grant Date Fair Value Per Share		Weighted Average Remaining Recognition Period (Years)
Nonvested at June 30, 2018	—	$	—	—
Granted	1,310,000	$	5.17
Vested	—	$	—
Forfeited	—	$	—
Nonvested at September 30, 2018	1,310,000	$	5.17	5.71
MSUs vested and expected to vest	920,140			5.63

Performance-based Restricted Stock Units ("PRSU")

In March 2017 and 2018, the Company granted 170,000 and 298,000 performance-based RSUs (“PRSUs”) to certain personnel. The number shares to be earned under the PRSU are determined based on the level of attainment of predetermined financial goals. The PRSU vests in four equal annual installments from the first anniversary date after the grant date if certain predetermined financial goals were met. The Company recorded approximately $0.6 million and $0.2 million of expenses for these PRSUs during the three months ended September 30, 2018, and 2017, respectively.

The following table summarizes the Company's PRSU activities for the three months ended September 30, 2018:



	Number of Performance-based Restricted Stock Units		Weighted Average Grant Date Fair Value Per Share		Weighted Average Remaining Recognition Period (Years)	Aggregate Intrinsic Value
Nonvested at June 30, 2018	422,300		$	16.63	2.06	$	6,013,552
Granted	—		—
Vested	—		—
Forfeited	(500	)	$	16.22
Nonvested at September 30, 2018	421,800		$	16.63	1.80	$	4,905,534
PRSUs vested and expected to vest	377,861				1.73	$	4,394,528

Stock Options

The Company did not grant any stock options during the three months ended September 30, 2018. The number of options expected to vest is the result of applying the pre-vesting forfeiture rate assumption to total outstanding options.

The following table summarizes the Company's stock option activities for the three months ended September 30, 2018:



					Weighted
			Weighted		Average
			Average		Remaining
	Number of		Exercise Price		Contractual	Aggregate
	Shares		Per Share		Term (in years)	Intrinsic Value
Outstanding at June 30, 2018	886,978		$	10.97	4.03	$	3,557,248
Exercised	(10,000	)	$	10.50		$	43,115
Outstanding at September 30, 2018	876,978		$	10.98	3.81	$	1,947,927
Options vested and expected to vest	876,978		$	10.98	3.81	$	1,947,927
Exercisable at September 30, 2018	876,978		$	10.98	3.81	$	1,947,927

Share-based Compensation Expense

The total share-based compensation expense recognized in the condensed consolidated statements of operations for the periods presented was as follows:



	Three Months Ended September 30,
	2018		2017
	(in thousands)
Cost of goods sold	$	497	$	316
Research and development	632		362
Selling, general and administrative	2,000		1,330
	$	3,129	$	2,008

As of September 30, 2018, total unrecognized compensation cost under the Company's equity plans was $16.7 million, which is expected to be recognized over a weighted-average period of 3.0 years.