(13) STOCK-BASED COMPENSATION

The Company adopted a nonqualified incentive stock option plan (the “BancFirst ISOP”) in May 1986. The Company amended the BancFirst ISOP to increase the number of shares to be issued under the plan to 3,200,000 shares in May 2016. At December 31, 2016, 215,735 shares were available for future grants. The BancFirst ISOP will terminate on December 31, 2019. The options vest and are exercisable beginning four years from the date of grant at the rate of 25% per year for four years. Options expire at the end of fifteen years from the date of grant. Options outstanding as of December 31, 2016 will become exercisable through the year 2023. The option price must be no less than 100% of the fair value of the stock relating to such option at the date of grant.

In June 1999, the Company adopted the BancFirst Corporation Non-Employee Directors’ Stock Option Plan (the “BancFirst Directors’ Stock Option Plan”). Each non-employee director is granted an option for 10,000 shares. The Company amended the BancFirst Directors’ Stock Option Plan to increase the number of shares to be issued under the plan to 260,000 shares in May 2016. At December 31, 2016, 40,000 shares were available for future grants. The options vest and are exercisable beginning one year from the date of grant at the rate of 25% per year for four years, and expire at the end of fifteen years from the date of grant. Options outstanding as of December 31, 2016 will become exercisable through the year 2020. The option price must be no less than 100% of the fair value of the stock relating to such option at the date of grant.

The Company currently uses newly issued shares for stock option exercises, but reserves the right to use shares purchased under the Company’s Stock Repurchase Program (the “SRP”) in the future.

The following table is a summary of the activity under both the BancFirst ISOP and the BancFirst Directors’ Stock Option Plan:

						Wgtd. Avg.
				Wgtd. Avg.		Remaining	Aggregate
				Exercise		Contractual	Intrinsic
	Options			Price		Term	Value
	(Dollars in thousands, except option data)
Year Ended December 31, 2016
Outstanding at December 31, 2015		1,018,149		$	40.69
Options granted		30,000			58.08
Options exercised		(310,699	)		31.28
Options canceled, forfeited, or expired		(30,000	)		55.88
Outstanding at December 31, 2016		707,450			44.92	9.59Yrs	$	34,049
Exercisable at December 31, 2016		325,200			37.19	6.78Yrs	$	18,167
Year Ended December 31, 2015
Outstanding at December 31, 2014		1,029,657		$	36.55
Options granted		133,000			59.37
Options exercised		(120,758	)		26.60
Options canceled, forfeited, or expired		(23,750	)		37.16
Outstanding at December 31, 2015		1,018,149			40.69	8.84Yrs	$	18,251
Exercisable at December 31, 2015		499,599			32.98	5.53Yrs	$	12,812

The following table has additional information regarding options granted and options exercised under both the BancFirst ISOP and the BancFirst Directors’ Stock Option Plan:

	Year Ended December 31,
	2016		2015		2014
	(Dollars in thousands, except per share data)
Weighted average grant-date fair value per share of options granted	$	11.92	$	11.72	$	12.27
Total intrinsic value of options exercised		12,230		4,376		5,597
Cash received from options exercised		9,720		3,212		4,870
Tax benefit realized from options exercised		4,731		1,693		2,165

The fair value of each option grant is estimated on the date of grant using the Black-Scholes option-pricing model and is based on certain assumptions including risk-free rate of return, dividend yield, stock price volatility and the expected term. The fair value of each option is expensed over its vesting period.

The following table is a summary of the Company’s recorded stock-based compensation expense:

	Year Ended December 31,
	2016		2015		2014
	(Dollars in thousands)
Stock-based compensation expense	$	1,636	$	1,717	$	1,676
Tax benefit		633		664		648
Stock-based compensation expense, net of tax	$	1,003	$	1,053	$	1,028

The Company will continue to amortize the unearned stock-based compensation expense over the remaining vesting period of approximately seven years. The following table shows the unearned stock-based compensation expense:

	December 31, 2016
	(Dollars in thousands)
Unearned stock-based compensation expense	$	2,770

The following table shows the assumptions used for computing stock-based compensation expense under the fair value method:

Year Ended December 31,

2016

2015

2014

Risk-free interest rate

1.46 to 2.02%

1.83 to 2.26%

2.10 to 2.54%

Dividend yield

2.00

Stock price volatility

20.41 to 21.78%

18.23 to 21.08%

18.03 to 18.98%

Expected term

10 Yrs

The risk-free interest rate is determined by reference to the spot zero-coupon rate for the U.S. Treasury security with a maturity similar to the expected term of the options. The dividend yield is the expected yield for the expected term. The stock price volatility is estimated from the recent historical volatility of the Company’s stock. The expected term is estimated from the historical option exercise experience.

In May 1999, the Company adopted the BancFirst Corporation Directors’ Deferred Stock Compensation Plan (the “BancFirst Deferred Stock Compensation Plan”). The Company amended the BancFirst Deferred Stock Compensation Plan to increase the number of shares to be issued under the plan to 111,110 shares in May 2016. Under the plan, directors and members of the community advisory boards of the Company and its subsidiaries may defer up to 100% of their board fees. They are credited for each deferral with a number of stock units based on the current market price of the Company’s stock, which accumulate in an account until such time as the director or community board member terminates serving as a board member. Shares of common stock of the Company are then distributed to the terminating director or community board member based upon the number of stock units accumulated in his or her account. The number of shares of common stock distributed from the BancFirst Deferred Stock Compensation Plan was 2,790 and 622 during the years ended December 31, 2016 and 2015, respectively.

A summary of the accumulated stock units is as follows:

	December 31,
	2016		2015
Accumulated stock units		70,022		66,376
Average price	$	41.74	$	39.64