Investments

The aggregate values of investment securities at September 30, 2013, and December 31, 2012, along with unrealized gains and losses determined on an individual security basis are as follows:



	Cost		Gross unrealized gains		Gross unrealized losses		Fair value
	(dollars in thousands)
Investment securities available for sale
September 30, 2013
U.S. Treasury	$	448,201	$	372	$	41	$	448,532
Government agency	2,583,888		2,320		1,428		2,584,780
Mortgage-backed securities	2,131,099		5,452		30,519		2,106,032
Equity securities	543		20,681		—		21,224
State, county and municipal	186		1		—		187
Other	857		—		27		830
Total investment securities available for sale	$	5,164,774	$	28,826	$	32,015	$	5,161,585
December 31, 2012
U.S. Treasury	$	823,241	$	403	$	12	$	823,632
Government agency	3,052,040		3,501		337		3,055,204
Mortgage-backed securities	1,315,211		14,787		341		1,329,657
Equity securities	543		15,822		—		16,365
State, county and municipal	546		4		—		550
Other	838		—		18		820
Total investment securities available for sale	$	5,192,419	$	34,517	$	708	$	5,226,228
Investment securities held to maturity
September 30, 2013
Mortgage-backed securities	$	1,013	$	67	$	—	$	1,080
December 31, 2012
Mortgage-backed securities	$	1,342	$	133	$	27	$	1,448

Investments in mortgage-backed securities primarily represent securities issued by the Government National Mortgage Association, Federal National Mortgage Association and Federal Home Loan Mortgage Corporation.

The following table provides the maturity distribution for non-amortizing securities. Repayments of mortgage-backed securities are dependent on the repayments of the underlying loan balances. Equity securities do not have a stated maturity date.



	September 30, 2013				December 31, 2012
	Cost		Fair value		Cost		Fair value
	(dollars in thousands)
Investment securities available for sale
Amortizing securities maturing in:
One year or less	$	864,992	$	865,925	$	2,285,159	$	2,286,403
One through five years	2,168,080		2,168,344		1,590,608		1,592,923
Five through 10 years	60		60		898		880
Over 10 years	—		—		—		—
Mortgage-backed securities	2,131,099		2,106,032		1,315,211		1,329,657
Equity securities	543		21,224		543		16,365
Total investment securities available for sale	$	5,164,774	$	5,161,585	$	5,192,419	$	5,226,228
Investment securities held to maturity
Mortgage-backed securities held to maturity	$	1,013	$	1,080	$	1,342	$	1,448

For each period presented, securities gains (losses) include the following:



	Three months ended September 30				Nine months ended September 30
	2013		2012		2013		2012
	(dollars in thousands)
Gross gains on sales of investment securities available for sale	$	—	$	31	$	—	$	36
Gross losses on sales of investment securities available for sale	—		—		—		(2		)
Other than temporary impairment loss on equity securities	—		—		—		(45		)
Total securities gains (losses)	$	—	$	31	$	—	$	(11	)

The following table provides information regarding securities with unrealized losses as of September 30, 2013, and December 31, 2012.



	Less than 12 months				12 months or more				Total
	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
	(dollars in thousands)
September 30, 2013
Investment securities available for sale:
U.S. Treasury	$	51,836	$	41	$	—	$	—	$	51,836	$	41
Government agency	953,103		1,428		—		—		953,103		1,428
Mortgage-backed securities	1,820,909		29,712		27,949		807		1,848,858		30,519
Other	830		27		—		—		830		27
Total	$	2,826,678	$	31,208	$	27,949	$	807	$	2,854,627	$	32,015
Investment securities held to maturity:
Mortgage-backed securities	$	—	$	—	$	—	$	—	$	—	$	—
December 31, 2012
Investment securities available for sale:
U.S. Treasury	$	120,045	$	12	$	—	$	—	$	120,045	$	12
Government agency	407,498		337		—		—		407,498		337
Mortgage-backed securities	135,880		214		9,433		127		145,313		341
Other	820		18		—		—		820		18
Total	$	664,243	$	581	$	9,433	$	127	$	673,676	$	708
Investment securities held to maturity:
Mortgage-backed securities	$	—	$	—	$	17	$	27	$	17	$	27

Investment securities with an aggregate fair value of $27,949 have had continuous unrealized losses for more than 12 months as of September 30, 2013, with an aggregate unrealized loss of $807. These 17 investments are mortgage-backed securities. None of the unrealized losses identified as of September 30, 2013, or December 31, 2012, relate to the marketability of the securities or the issuer’s ability to honor redemption obligations. For all periods presented, BancShares had the ability and intent to retain these securities for a period of time sufficient to recover all unrealized losses. Therefore, none of the securities were deemed to be other than temporarily impaired.

Investment securities having an aggregate carrying value of $2,547,581 at September 30, 2013, and $2,351,072 at December 31, 2012, were pledged as collateral to secure public funds on deposit and certain short-term borrowings, and for other purposes as required by law.