Investments

The following table provides cost or amortized cost, gross unrealized gains, gross unrealized losses and fair value for our investment portfolio:



(Dollars in millions)	Cost or amortized cost
			Gross unrealized				Fair value
At March 31, 2015			gains		losses		Fair value
Fixed maturity securities:
Corporate	$	5,152	$	449	$	8	$	5,593
States, municipalities and political subdivisions	3,289		183		2		3,470
Commercial mortgage-backed	269		16		—		285
Government-sponsored enterprises	227		—		3		224
Foreign government	10		—		—		10
Convertibles and bonds with warrants attached	7		—		—		7
United States government	7		—		—		7
Subtotal	8,961		648		13		9,596
Equity securities:
Common equities	2,595		2,014		11		4,598
Nonredeemable preferred equities	153		38		—		191
Subtotal	2,748		2,052		11		4,789
Total	$	11,709	$	2,700	$	24	$	14,385
At December 31, 2014
Fixed maturity securities:
Corporate	$	5,117	$	420	$	11	$	5,526
States, municipalities and political subdivisions	3,267		178		2		3,443
Commercial mortgage-backed	250		9		—		259
Government-sponsored enterprises	213		—		5		208
Foreign government	10		—		—		10
Convertibles and bonds with warrants attached	7		—		—		7
United States government	7		—		—		7
Subtotal	8,871		607		18		9,460
Equity securities:
Common equities	2,583		2,099		3		4,679
Nonredeemable preferred equities	145		35		1		179
Subtotal	2,728		2,134		4		4,858
Total	$	11,599	$	2,741	$	22	$	14,318

The net unrealized investment gains in our fixed-maturity portfolio are primarily the result of the continued low interest rate environment that increased the fair value of our fixed-maturity portfolio. At March 31, 2015, we had $25 million of short-term investments, which consisted of commercial paper, that had no gross unrealized gains or losses. At December 31, 2014, we held no short-term investments. The seven largest unrealized investment gains in our common stock portfolio are from Exxon Mobil Corporation (NYSE:XOM), Honeywell International Incorporated (NYSE:HON), BlackRock Inc. (NYSE:BLK), Apple Inc. (Nasdaq:AAPL), The Procter & Gamble Company (NYSE:PG), RPM International (NYSE:RPM), and 3M Company (NYSE:MMM), which had a combined gross unrealized gain of $605 million. At March 31, 2015, Apple Inc. was our largest single common stock holding with a fair value of 3.8 percent of our publicly traded common stock portfolio and 1.2 percent of the total investment portfolio.

The table below provides fair values and gross unrealized losses by investment category and by the duration of the securities’ continuous unrealized loss positions:



(Dollars in millions)	Less than 12 months				12 months or more				Total
	Fair value		Unrealized losses		Fair value		Unrealized losses		Fair value		Unrealized losses
At March 31, 2015	Fair value		Unrealized losses		Fair value		Unrealized losses		Fair value		Unrealized losses
Fixed maturity securities:
Corporate	$	211	$	6	$	64	$	2	$	275	$	8
States, municipalities and political subdivisions	115		2		58		—		173		2
Commercial mortgage-backed	2		—		2		—		4		—
Government-sponsored enterprises	18		—		156		3		174		3
Subtotal	346		8		280		5		626		13
Equity securities:
Common equities	168		11		—		—		168		11
Nonredeemable preferred equities	5		—		15		—		20		—
Subtotal	173		11		15		—		188		11
Total	$	519	$	19	$	295	$	5	$	814	$	24
At December 31, 2014
Fixed maturity securities:
Corporate	$	261	$	8	$	90	$	3	$	351	$	11
States, municipalities and political subdivisions	17		—		135		2		152		2
Commercial mortgage-backed	3		—		23		—		26		—
Government-sponsored enterprises	11		—		181		5		192		5
Subtotal	292		8		429		10		721		18
Equity securities:
Common equities	85		3		—		—		85		3
Nonredeemable preferred equities	16		—		17		1		33		1
Subtotal	101		3		17		1		118		4
Total	$	393	$	11	$	446	$	11	$	839	$	22

The following table provides investment income, realized investment gains and losses, the change in unrealized investment gains and losses, and other items:



(Dollars in millions)	Three months ended March 31,
	2015			2014
Investment income:
Interest	$	105		$	104
Dividends	36			32
Other	—			1
Total	141			137
Less investment expenses	2			2
Total	$	139		$	135

Realized investment gains and losses summary:
Fixed maturities:
Gross realized gains	$	3		$	2
Gross realized losses	—			(1		)
Other-than-temporary impairments	—			—
Equity securities:
Gross realized gains	44			18
Gross realized losses	(1		)	—
Other-than-temporary impairments	—			(1		)
Other	1			4
Total	$	47		$	22

Change in unrealized investment gains and losses:
Fixed maturities	$	46		$	88
Equity securities	(89		)	29
Less income taxes	15			(41		)
Total	$	(28	)	$	76

During the three months ended March 31, 2015, there were no equity securities and no fixed-maturity securities other-than-temporarily impaired. There were no credit losses on fixed-maturity securities for which a portion of other-than-temporary impairment (OTTI) has been recognized in other comprehensive income for the three months ended March 31, 2015 and 2014. At March 31, 2015, 70 fixed-maturity investments with a total unrealized loss of

$5 million had been in an unrealized loss position for 12 months or more. Of that total, no fixed-maturity investments had fair values below 70 percent of amortized cost. Two equity investments with a total unrealized loss of less than $1 million had been in an unrealized loss position for 12 months or more as of March 31, 2015. Of that total, no equity investments were trading below 70 percent of cost.

During 2014, we other-than-temporarily impaired six fixed-maturity securities. At December 31, 2014, 144 fixed-maturity investments with a total unrealized loss of $10 million had been in an unrealized loss position for 12 months or more. Of that total, no fixed-maturity investments had fair values below 70 percent of amortized cost. There were three equity security investments in an unrealized loss position for 12 months or more with a total unrealized loss of $1 million as of December 31, 2014. Of that total, no equity security investments had fair values below 70 percent of cost.