11. Stock-based compensation plans

Stock-based compensation expense was $67 million in 2015, $65 million in 2014 and $55 million in 2013. The Company recognized income tax benefits related to stock-based compensation of $29 million in 2015, $31 million in 2014 and $29 million in 2013.

The Company’s equity incentive compensation plan allows for the issuance of various forms of stock-based compensation, including stock options, restricted stock, restricted stock units and performance-based awards. At December 31, 2015 and 2014, respectively, there were 3,954,712 and 4,398,496 shares available for future grant under the Company’s equity incentive compensation plan.

Restricted stock awards

Restricted stock awards are comprised of restricted stock and restricted stock units. Restricted stock awards granted in 2015 and 2014 vest over three years. Restricted stock awards granted prior to 2014 generally vest over four years. A portion of restricted stock awards granted in 2015 and 2014 require a performance condition to be met before such awards vest. Unrecognized compensation expense associated with restricted stock was $14 million as of December 31, 2015 and is expected to be recognized over a weighted-average period of approximately one year. The Company may issue restricted shares from treasury stock to the extent available or issue new shares. The number of restricted shares issued was 218,183 in 2015, 221,822 in 2014 and 269,755 in 2013, with a weighted-average grant date fair value of $24,726,000 in 2015, $24,765,000 in 2014 and $27,716,000 in 2013. Unrecognized compensation expense associated with restricted stock units was $6 million as of December 31, 2015 and is expected to be recognized over a weighted-average period of approximately one year. The number of restricted stock units issued was 324,772 in 2015, 299,525 in 2014 and 315,316 in 2013, with a weighted-average grant date fair value of $37,070,000, $33,406,000 and $32,380,000, respectively.

A summary of restricted stock and restricted stock unit activity follows:


	Restricted Stock Units Outstanding			Weighted- Average Grant Price		Restricted Stock Outstanding			Weighted- Average Grant Price
Unvested at January 1, 2015		789,411		$	99.53		761,645		$	96.36
Granted		324,772			114.14		218,183			113.33
Assumed in acquisition		215,215			119.85		—			—
Vested		(357,457	)		98.35		(325,518	)		92.68
Cancelled		(3,443	)		100.95		(28,422	)		104.60

Unvested at December 31, 2015		968,498		$	109.38		625,888		$	103.82

Stock option awards

Stock options issued generally vest over four years and are exercisable over terms not exceeding ten years and one day. The Company used an option pricing model to estimate the grant date present value of stock options granted. Stock options granted in 2015, 2014 and 2013 were not significant.

A summary of stock option activity follows:


	Stock Options Outstanding			Weighted-Average				Aggregate Intrinsic Value (In thousands)
	Stock Options Outstanding			Exercise Price		Life (In Years)		Aggregate Intrinsic Value (In thousands)
Outstanding at January 1, 2015		3,432,870		$	105.31
Granted		200			113.16
Assumed in acquisition		1,843,159			156.82
Exercised		(954,684	)		107.06
Expired		(97,835	)		137.50

Outstanding at December 31, 2015		4,223,710		$	126.65		1.7	$	43,761

Exercisable at December 31, 2015		4,223,266		$	126.65		1.7	$	43,755

For 2015, 2014 and 2013, M&T received $93 million, $127 million and $172 million, respectively, in cash and realized tax benefits from the exercise of stock options of $6 million, $9 million and $12 million, respectively. The intrinsic value of stock options exercised during those periods was $17 million, $26 million and $34 million, respectively. As of December 31, 2015, the amount of unrecognized compensation cost related to non-vested stock options was not significant. The total grant date fair value of stock options vested during 2015, 2014 and 2013 was not significant. Upon the exercise of stock options, the Company may issue shares from treasury stock to the extent available or issue new shares.

Stock purchase plan

The stock purchase plan provides eligible employees of the Company with the right to purchase shares of M&T common stock at a discount through accumulated payroll deductions. In connection with the employee stock purchase plan, 2,500,000 shares of M&T common stock were authorized for issuance under a plan adopted in 2013. There were 89,384 shares issued in 2015 and 85,761 shares issued in 2014. No shares were issued in 2013. For 2015 and 2014, M&T received $9,296,000 and $8,607,000, respectively, in cash for shares purchased through the employee stock purchase plan. Compensation expense recognized for the stock purchase plan was not significant in 2015, 2014 or 2013.

Deferred bonus plan

The Company provided a deferred bonus plan pursuant to which eligible employees could elect to defer all or a portion of their annual incentive compensation awards and allocate such awards to several investment options, including M&T common stock. Participants could elect the timing of distributions from the plan. Such distributions are payable in cash with the exception of balances allocated to M&T common stock which are distributable in the form of M&T common stock. Shares of M&T common stock distributable pursuant to the terms of the deferred bonus plan were 26,365 and 29,297 at December 31, 2015 and 2014, respectively. The obligation to issue shares is included in “common stock issuable” in the consolidated balance sheet.

Directors’ stock plan

The Company maintains a compensation plan for non-employee members of the Company’s boards of directors and directors advisory councils that allows such members to receive all or a portion of their compensation in shares of M&T common stock. Through December 31, 2015, 225,763 shares had been issued in connection with the directors’ stock plan.

Through acquisitions, the Company assumed obligations to issue shares of M&T common stock related to deferred directors compensation plans. Shares of common stock issuable under such plans were 10,279 and 12,033 at December 31, 2015 and 2014, respectively. The obligation to issue shares is included in “common stock issuable” in the consolidated balance sheet.