STOCKHOLDERS’ EQUITY AND SHARE-BASED COMPENSATION EXPENSE

Share-based Compensation Plans

The Company has a share-based compensation program, most recently the 2000 Amended and Restated Equity Incentive Plan (the “Plan”), that provides the Board of Directors broad discretion in creating equity incentives for employees, officers, directors and consultants. This program includes incentive and non-qualified stock options and non-vested stock awards (also known as restricted stock) granted under various stock plans. As of June 30, 2014, the Company had approximately 4.4 million shares of common stock reserved for future issuance under its share-based compensation plans. New shares are issued as a result of stock option exercises, restricted stock units vesting and restricted stock award grants.

The Company recognized share-based compensation expense as follows (in thousands):



	Three Months Ended June 30,				Six Months Ended June 30,
	2014		2013		2014		2013
Costs of product sales	$	660	$	262	$	1,197	$	429
Research and development	637		202		1,144		531
Selling, general and administrative	1,830		812		3,931		2,150
Total share-based compensation expense	$	3,127	$	1,276	$	6,272	$	3,110

As of June 30, 2014, $17.8 million of total unrecognized share-based compensation expense related to non-vested awards is expected to be recognized over the respective vesting terms of each award through 2018. The weighted‑average terms of the unrecognized share-based compensation expense are 2.3 years for stock options and 2.1 years for restricted stock.

Performance-Based Awards

The Company's share-based awards program includes performance-based restricted stock awards ("PRSUs") that vest based upon the achievement of certain performance criteria and a service vesting criteria following the achievement of performance criteria. Performance criteria include various operational criteria of the Company such as revenues, earnings before interest, taxes, depreciation and amortization, product launches, and similar criteria, either on a Company-wide or segment specific basis. The service vesting criteria ranges from six months to four years. The Company recognizes the fair value of these awards to the extent the achievement of the related performance criteria is estimated to be probable. If a performance criteria is subsequently determined to not be probable of achievement, any related expense is reversed in the period such determination is made. Conversely, if a performance criteria is not currently expected to be achieved but is later determined to be probable of achievement, a “catch-up” entry is recorded in the period such determination is made for the expense that would have been recognized had the performance criteria been probable of achievement since the grant of the award.

As of June 30, 2014, there were 1,194,100 PRSUs outstanding with an average grant date fair value of $5.93 per PRSU. The Company expects that it is probable that 874,686 of these PRSUs will vest and that the related unrecognized stock compensation expense of $2.9 million will be recognized over the next 4 years. Changes in the Company’s assessment of the probability of achievement of performance criteria could have a material effect on the results of operations in future periods. There were no changes in estimate related to the probability of vesting or recognition of expense related to PRSUs during either of the periods ended June 30, 2014 or 2013.

For additional information concerning the Company's share-based compensation plans, including performance-based awards programs, see Note 13, "Stockholders' Equity and Share-Based Compensation Expense", to the consolidated financial statements in Part II, Item 8 of the Company's 2013 Annual Report on Form 10-K.