The Company has granted nonstatutory stock options to certain key employees under the Plans. The Plans are administered by the Compensation Committee of the Board of Directors. Stock options are generally non-qualified and are at exercise prices not less than 100% of the average per share fair market value on the date of grant. Stock-based compensation awards granted under the Company's stock incentive plans are generally subject to a vesting period from the date of the grant ranging from 1 - 3 years. Currently outstanding options expire on various dates through November 2020.

The following table sets forth information relating to such options during 2015, 2014, and 2013:



Stock Option Activity	Number Of Shares		Average Exercise Price		Weighted- Average Grant Date Fair Value
Balance, January 1, 2013	4,024,484		$	32.33
Options exercised	(1,464,294	)	23.46
Options forfeited	(95,139	)	52.17
Options terminated	(1,381	)	42.26
Options granted	421,385		76.70		$	19.26
Balance, December 31, 2013	2,885,055		42.60
Options exercised	(793,359	)	29.53
Options forfeited	(42,424	)	68.07
Options granted	474,518		93.39		20.12
Balance, December 31, 2014	2,523,790		55.77
Options exercised	(728,408	)	36.85
Options forfeited	(25,000	)	92.57
Options terminated	(500	)	100.29
Options granted	550,805		96.01		19.28
Balance, December 31, 2015	2,320,687

The following is a summary of nonvested option activity for the year ended December 31, 2015:



Stock Option Activity	Number Of Shares		Weighted- Average Grant Date Fair Value
Nonvested options outstanding at beginning of year	959,842		$	20.12
Granted	550,805		19.28
Vested	(511,146	)	18.83
Forfeited	(25,500	)	15.37
Nonvested options outstanding at end of year	974,001

As of December 31, 2015, the intrinsic value (the difference between the exercise price and the market price) for options outstanding was $66.7 million and for options exercisable was $59.9 million. The total intrinsic value of all options exercised during the years ended December 31, 2015, 2014 and 2013 was $46.1 million, $53.6 million and $83.2 million, respectively. A summary of our stock options outstanding and exercisable at December 31, 2015, follows:



Exercise Price Range	Number Outstanding	Number Exercisable	Outstanding Weighted- Average Remaining Contractual Life (Years)	Exercisable Weighted- Average Exercise Price
$40 - $50	985,206	985,206	0.92	$	45.30
$60 - $70	16,499	16,499	1.94	66.70
$70 - $80	332,279	209,074	2.32	76.66
$80 - $90	1,631	890	2.49	84.74
$90 - $100	957,572	131,072	3.97	92.94
$100 - $110	27,500	6,875	3.16	100.29
	2,320,687	1,349,616

At December 31, 2015, the weighted-average remaining contractual term of all options outstanding and exercisable was 2.41 years.

Options Granted The Company granted approximately 0.6 million, 0.5 million, and 0.4 million nonstatutory stock options in 2015, 2014, and 2013, respectively, under the Plans.

For the years ended December 31, 2015, 2014 and 2013, Grace recognized non-cash stock-based compensation expense of $9.9 million, $12.0 million and $12.7 million, respectively, which is included in selling, general and administrative expense.

Grace values options using the Black-Scholes option-pricing model, which was developed for use in estimating the fair value of traded options. The risk-free rate is based on the U.S. Treasury yield curve published as of the grant date, with maturities approximating the expected term of the options. The expected term of the options is estimated using the simplified method as allowed by ASC 718-20, whereby the average between the vesting period and contractual term is used. The expected volatility was estimated using both actual stock volatility and the volatility of an industry peer group. Grace believes its actual stock volatility in the last several years may not be representative of expected future volatility because of its previous status in Chapter 11. The following summarizes the assumptions used for estimating the fair value of stock options granted during 2015, 2014 and 2013, respectively.



	2015	2014	2013
Expected volatility	23.0% - 27.2%	28.2% - 28.7%	32.3% - 34.3%
Weighted average expected volatility	24.5%	28.6%	33.3%
Expected term	3.00 - 4.00 years	3.00 - 4.00 years	3.00 - 4.00 years
Risk-free rate	1.30%	1.25%	0.61%
Dividend yield	—%	—%	—%

Total unrecognized stock-based compensation expense at December 31, 2015, was $5.8 million and the weighted-average period over which this expense will be recognized is 0.8 years.

Restricted Stock and Performance Based Units During 2015 the Company granted 123,846 Restricted Stock Units (RSUs) and 1,864 Performance Based Units (PBUs) under the Company's Long-term Incentive Plan (LTIP). During 2014 the Company granted 110,993 PBUs under the LTIP. During 2013 the Company granted 111,770 PBUs under the LTIP. During 2015, 2014, and 2013, 10,641, 8,570, and 5,513 awards were forfeited, respectively. The awards cliff vest on December 31, 2017, 2016, and 2015, subject to continued employment through the payment date, and have a weighted average grant date fair value of $96.12, $92.92, and $76.66, respectively. The Company anticipates that approximately 53% of the awards granted in 2015 will be settled in common stock, and approximately 47% will be settled in cash, assuming full vesting. The Company anticipates that approximately 53% of the PBUs granted in 2014 will be settled in common stock and approximately 47% will be settled in cash, assuming full vesting. The Company anticipates that approximately 54% of the PBUs granted in 2013 will be settled in common stock and approximately 46% will be settled in cash, assuming full vesting.

PBUs and RSUs are recorded at fair value at the date of grant. The common stock settled portion is considered an equity award with the payout being valued based on the Company’s stock price on the grant date. The cash settled portion of the award is considered a liability award with payout being remeasured each reporting period based on the Company’s current stock price. PBU equity and cash awards are remeasured each reporting period based on the expected payout of the award, which may range from 0% to 200% of the targets for such awards; therefore, these portions of the awards are subject to volatility until the payout is finally determined at the end of the performance period. During 2015, 2014, and 2013, the Company recognized $5.8 million, $3.5 million, and $1.7 million in compensation expense for these awards. As of December 31, 2015, $11.1 million of total unrecognized compensation expense related to the awards is expected to be recognized over the remaining weighted-average service period of 1.7 years.