e. Stock Options. Under stockholder approved stock-based plans, stock options, stock appreciation rights, restricted stock and restricted stock units may be granted to officers, directors and other key employees. At March 31, 2016, 1.2 million shares of unissued common stock of the company were available for granting under these plans.

The fair value of stock option awards was estimated using the Black-Scholes option pricing model with the following assumptions and weighted-average fair values:


	Three Months Ended March 31,
	2016			2015
Weighted-average fair value of grant	$	4.53		$	9.12
Risk-free interest rate		1.29	%		1.28	%
Expected volatility		51.30	%		45.46	%
Expected life of options in years		4.90			4.92
Expected dividend yield		—			—

Restricted stock unit awards may contain time-based units, performance-based units or a combination of both. Each performance-based unit will vest into zero to 2.0 shares depending on the degree to which the performance goals are met. Compensation expense resulting from these awards is recognized as expense ratably for each installment from the date of grant until the date the restrictions lapse and is based on the fair market value at the date of grant and the probability of achievement of the specific performance-related goals.

The company records all share-based expense in selling, general and administrative expense.

During the three months ended March 31, 2016 and 2015, the company recorded $3.2 million and $4.4 million of share-based compensation expense, respectively, which is comprised of $2.6 million and $1.8 million of restricted stock unit expense and $.6 million and $2.6 million of stock option expense, respectively.

A summary of stock option activity for the three months ended March 31, 2016 follows (shares in thousands):


Options	Shares			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (years)		Aggregate Intrinsic Value ($ in millions)
Outstanding at December 31, 2015		2,723		$	27.88
Granted		11			10.85
Exercised		—			—
Forfeited and expired		(516	)		38.36

Outstanding at March 31, 2016		2,218			25.36		3.08	$	—

Expected to vest at March 31, 2016		684			25.55		4.52		—

Exercisable at March 31, 2016		1,498			25.32		2.37		—

The aggregate intrinsic value represents the total pretax value of the difference between the company’s closing stock price on the last trading day of the period and the exercise price of the options, multiplied by the number of in-the-money stock options that would have been received by the option holders had all option holders exercised their options on March 31, 2016. The intrinsic value of the company’s stock options changes based on the closing price of the company’s stock. The total intrinsic value of options exercised for the three months ended March 31, 2016 and 2015 was zero and $.6 million, respectively. As of March 31, 2016, $3.3 million of total unrecognized compensation cost related to stock options is expected to be recognized over a weighted-average period of 1.7 years.

A summary of restricted stock unit activity for the three months ended March 31, 2016 follows (shares in thousands):


	Restricted Stock Units			Weighted- Average Grant-Date Fair Value
Outstanding at December 31, 2015		469		$	23.57
Granted		1,156			10.06
Vested		(154	)		20.17
Forfeited and expired		(3	)		24.40

Outstanding at March 31, 2016		1,468			13.32

The fair value of restricted stock units is determined based on the trading price of the company’s common shares on the date of grant. The aggregate weighted-average grant-date fair value of restricted stock units granted during the three months ended March 31, 2016 and 2015 was $11.6 million and $8.8 million, respectively. As of March 31, 2016, there was $13.9 million of total unrecognized compensation cost related to outstanding restricted stock units granted under the company’s plans. That cost is expected to be recognized over a weighted-average period of 2.6 years. The aggregate weighted-average grant-date fair value of restricted share units vested during the three months ended March 31, 2016 and 2015 was $3.1 million and $1.8 million, respectively.

Common stock issued upon exercise of stock options or upon lapse of restrictions on restricted stock units are newly issued shares. Cash received from the exercise of stock options for the three months ended March 31, 2016 and 2015 was zero and $3.5 million, respectively. The company is currently not recognizing any tax benefits from the exercise of stock options or upon issuance of stock upon lapse of restrictions on restricted stock units in light of its tax position. Tax benefits resulting from tax deductions in excess of the compensation costs recognized are classified as financing cash flows.