Stock-based Compensation (Tables)

Total stock-based compensation expense recognized was as follows:

	For Years Ended December 31,
	2015		2014		2013
COR	$	47	$	48	$	49
R&D		60		62		67
SG&A		169		156		160
Acquisition charges		10		11		11
Total	$	286	$	277	$	287

We estimate the fair values for non-qualified stock options using the Black-Scholes-Merton option-pricing model with the following weighted average assumptions.

	For Years Ended December 31,
	2015			2014			2013
Weighted average grant date fair value, per share	$	9.49		$	8.13		$	6.78
Weighted average assumptions used:
Expected volatility		22	%		22	%		26	%
Expected lives (in years)		7.3			7.3			7.4
Risk-free interest rates		1.64	%		2.45	%		1.43	%
Expected dividend yields		2.52	%		2.72	%		2.56	%

Stock option and RSU transactions under our long-term incentive and director compensation plans during 2015 were as follows:

	Stock Options					RSUs
				Weighted Average					Weighted Average
				Exercise Price					Grant Date Fair
	Shares			per Share		Shares			Value per Share
Outstanding grants, December 31, 2014		57,647,446		$	32.84		17,303,815		$	35.24
Granted		11,913,832			53.95		2,679,437			53.22
Vested RSUs		—			—		(3,386,415	)		33.72
Forfeited and expired		(833,840	)		42.71		(541,295	)		36.94
Exercised		(11,953,455	)		31.33		—			—
Outstanding grants, December 31, 2015		56,773,983			37.45		16,055,542			38.51

Summarized information about stock options outstanding at December 31, 2015, is as follows:

		Stock Options Outstanding							Options Exercisable
		Number			Weighted Average		Weighted Average		Number		Weighted Average
Exercise Price		Outstanding		Remaining Contractual			Exercise Price		Exercisable		Exercise Price
Range		(Shares)			Life (Years)		per Share		(Shares)		per Share
$	14.47 to 20.00		3,499,029			3.1	$	14.96		3,499,029	$	14.96
	20.01 to 30.00		8,385,885			3.1		25.56		8,377,295		25.56
	30.01 to 40.00		21,215,903			6.0		33.00		12,732,409		33.21
	40.01 to 50.00		12,012,519			8.1		44.11		2,229,828		44.10
	50.01 to 58.98		11,660,647			9.1		53.96		1,521		55.41
	14.47 to 58.98		56,773,983			6.5		37.45		26,840,082		29.35

Summarized information as of December 31, 2015, about outstanding stock options that are vested and expected to vest, as well as stock options that are currently exercisable, is as follows:

	Outstanding Stock Options
	(Fully Vested and		Options
	Expected to Vest) (a)		Exercisable
Number of outstanding (shares)		55,421,103		26,840,082
Weighted average remaining contractual life (in years)		6.4		4.6
Weighted average exercise price per share	$	37.17	$	29.35
Intrinsic value (millions of dollars)	$	978	$	683

(a) Includes effects of expected forfeitures of approximately 1 million shares. Excluding the effects of expected forfeitures, the aggregate intrinsic value of stock options outstanding was $986 million.

Director deferred stock activity during 2015 was as follows:

	Director Deferred Stock (Shares)
Outstanding, December 31, 2014		135,722
New shares deferred		14,722
Issued		(7,531	)
Outstanding, December 31, 2015		142,913

Employee stock purchase plan transactions during 2015 were as follows:

	Employee Stock
	Purchase Plan
	(Shares)			Exercise Price
Outstanding grants, December 31, 2014		374,703		$	45.46
Granted		1,530,127			44.75
Exercised		(1,532,264	)		44.57
Outstanding grants, December 31, 2015		372,566			46.19

The table below reflects the changes in our treasury shares:

	Stock Options			RSUs			Treasury Shares
Balance, December 31, 2012								632,636,970
Repurchases								77,564,013
Shares used for:
Stock options/RSUs		(45,507,711	)		(5,741,981	)
Stock applied to taxes		—			1,461,422
ESPP		(2,386,834	)		—
Director deferred stock		—			—			(12,909	)
Total issued		(47,894,545	)		(4,280,559	)		(52,175,104	)
Balance, December 31, 2013								658,012,970

Repurchases								61,665,209
Shares used for:
Stock options/RSUs		(19,503,382	)		(5,609,627	)
Stock applied to exercises or taxes		6,618			1,408,701
ESPP		(1,784,184	)		—
Director deferred stock		—			—			(7,178	)
Total issued		(21,280,948	)		(4,200,926	)		(25,481,874	)
Balance, December 31, 2014								694,189,127

Repurchases								51,384,339
Shares used for:
Stock options/RSUs		(11,953,455	)		(3,386,415	)
Stock applied to exercises or taxes		8,562			845,164
ESPP		(1,532,264	)		—
Director deferred stock		—			—			(7,531	)
Total issued		(13,477,157	)		(2,541,251	)		(16,018,408	)
Balance, December 31, 2015								729,547,527

Shares available for future grants and reserved for issuance are summarized below:

	December 31, 2015
	Long-Term Incentive
	and Director			Employee Stock
Shares	Compensation Plans			Purchase Plan			Total
Reserved for issuance (a)		105,793,583			38,032,774			143,826,357
Shares to be issued upon exercise of outstanding options and RSUs (a)		(72,972,438	)		(372,566	)		(73,345,004	)
Available for future grants		32,821,145			37,660,208			70,481,353

(a) Includes 142,913 shares credited to directors’ deferred stock accounts that settle in shares of TI common stock. These shares are not included as grants outstanding at December 31, 2015.

The effects on cash flows were as follows:

	For Years Ended December 31,
	2015		2014		2013
Proceeds from common stock transactions	$	442	$	616	$	1,314
Tax benefit realized from stock options exercised		171		218		227