Note 3. Stock-Based Compensation

The Company accounts for all share-based payments in accordance with ASC Topic 718, "Compensation—Stock Compensation" ("ASC 718"). The stock‑based compensation expense related to the stock option plans and the Associate Stock Purchase Plan included in operating expenses was $1,132 and $1,116 for the thirteen week periods ended February 27, 2016 and February 28, 2015, respectively, and $2,388 and $2,848, respectively, for the twenty-six week periods ended February 27, 2016 and February 28, 2015. Tax benefits related to these expenses for the thirteen week periods ended February 27, 2016 and February 28, 2015 were $405 and $388, respectively, and for the twenty-six week periods ended February 27, 2016 and February 28, 2015 were $856 and $1,015, respectively.

The fair value of each option grant is estimated on the date of grant using the Black‑Scholes option pricing model with the following assumptions:



		Twenty-Six Weeks Ended
		February 27,			February 28,
		2016			2015
Expected life (in years)		3.9			3.9
Risk-free interest rate		1.09	%		1.09	%
Expected volatility		21.82	%		24.49	%
Expected dividend yield		2.40	%		1.70	%
Weighted-average grant-date fair value	$	8.03		$	14.06

A summary of the Company’s stock option activity for the twenty-six week period ended February 27, 2016 is as follows:



	Options	Weighted-Average Exercise Price per Share		Weighted-Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value
Outstanding on August 29, 2015	1,274	$	73.10
Granted	586		58.90
Exercised	(23)		43.74
Canceled/Forfeited	(56)		75.87
Outstanding on February 27, 2016	1,781	$	68.72	4.9	$	10,460
Exercisable on February 27, 2016	732	$	68.73	3.3	$	3,859

The unrecognized share‑based compensation cost related to stock option expense at February 27, 2016 was $9,296 and will be recognized over a weighted average period of 3.0 years. The total intrinsic value of options exercised, which represents the difference between the exercise price and market value of common stock measured at each individual exercise date, during the twenty-six week periods ended February 27, 2016 and February 28, 2015 was $481 and $2,330, respectively.

A summary of the non‑vested restricted share award (“RSA”) activity under the Company’s 2005 Omnibus Incentive Plan and 2015 Omnibus Incentive Plan for the twenty-six week period ended February 27, 2016 is as follows:



	Shares	Weighted-Average Grant-Date Fair Value
Non-vested restricted share awards at August 29, 2015	391	$	75.39
Granted	1		62.31
Vested	(108)		67.22
Canceled/Forfeited	(8)		78.03
Non-vested restricted share awards at February 27, 2016	276	$	78.47

The fair value of each RSA is the closing stock price on the New York Stock Exchange of the Company’s Class A common stock on the date of grant. Upon vesting, a portion of the RSA award may be withheld to satisfy the minimum statutory withholding taxes. The remaining RSAs will be settled in shares of the Company’s Class A common stock when vested. Stock‑based compensation expense recognized for the RSAs was $1,473 and $1,762 for the thirteen week periods ended February 27, 2016 and February 28, 2015, respectively, and $3,199 and $4,529 for the twenty-six week periods ended February 27, 2016 and February 28, 2015, respectively. The unrecognized compensation cost related to RSAs at February 27, 2016 was $12,262 and will be recognized over a weighted average period of 2.7 years.

A summary of the Company’s non-vested Restricted Stock Unit (“RSU”) award activity for the twenty-six week period ended February 27, 2016 is as follows:



	Shares		Weighted- Average Grant- Date Fair Value
Non-vested restricted stock unit awards at August 29, 2015	62	$	55.09
Granted	207		58.83
Vested	(1)		58.87
Canceled/Forfeited	(3)		58.81
Non-vested restricted stock unit awards at February 27, 2016	265	$	57.95

The fair value of each RSU is the closing stock price on the New York Stock Exchange of the Company’s Class A common stock on the date of grant. Upon vesting, a portion of the RSU award may be withheld to satisfy the minimum statutory withholding taxes. The remaining RSUs will be settled in shares of the Company’s Class A common stock when vested. These awards accrue dividend equivalents on outstanding units (in the form of additional stock units) based on dividends declared on the Company’s Class A common stock and these dividend equivalents convert to unrestricted common stock on the vesting dates of the underlying RSUs. The dividend equivalents are not included in the RSU table above. Stock‑based compensation expense recognized for the RSUs was $773 and $285 for the thirteen week periods ended February 27, 2016 and February 28, 2015, respectively, and $1,412 and $825 for the twenty-six week periods ended February 27, 2016 and February 28, 2015, respectively. The unrecognized compensation cost related to the RSUs at February 27, 2016 was $10,268 and is expected to be recognized over a weighted average period of 3.6 years.