INVESTMENT SECURITIES

A summary of the Corporation’s investment securities follows:



(in millions)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
September 30, 2018
Investment securities available-for-sale:
U.S. Treasury and other U.S. government agency securities	$	2,731	$	—	$	32	$	2,699
Residential mortgage-backed securities (a)	9,496		6		339		9,163
Total investment securities available-for-sale	$	12,227	$	6	$	371	$	11,862

December 31, 2017
Investment securities available-for-sale:
U.S. Treasury and other U.S. government agency securities	$	2,743	$	—	$	16	$	2,727
Residential mortgage-backed securities (a)	8,230		22		128		8,124
State and municipal securities	5		—		—		5
Equity and other non-debt securities	83		1		2		82
Total investment securities available-for-sale (b)	$	11,061	$	23	$	146	$	10,938
Investment securities held-to-maturity (c):
Residential mortgage-backed securities (a)	$	1,266	$	—	$	20	$	1,246


(a)	Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.


(b)	Included auction-rate securities at amortized cost and fair value of $51 million and $49 million, respectively, as of December 31, 2017.


(c)	The amortized cost of investment securities held-to-maturity included net unrealized losses of $9 million at December 31, 2017 related to securities transferred from available-for-sale in 2014, which are included in accumulated other comprehensive loss.

In connection with the adoption of ASU 2016-01 on January 1, 2018, cumulative unrealized gains and losses on available-for-sale equity and other non-debt securities were reclassified to retained earnings and the carrying value was reclassified to other short-term investments. Additionally, the Corporation transferred residential mortgage-backed securities with a book value of approximately $1.3 billion from held-to-maturity to available-for-sale upon the adoption of ASU 2017-12. For additional information about the adoption of ASU 2016-01, refer to note 1.

A summary of the Corporation’s investment securities in an unrealized loss position as of September 30, 2018 and December 31, 2017 follows:



	Temporarily Impaired
	Less than 12 Months				12 Months or more					Total
(in millions)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
September 30, 2018
U.S. Treasury and other U.S. government agency securities	$	1,852	$	30	$	182	$	2		$	2,034	$	32
Residential mortgage-backed securities (a)	4,280		106		4,363		233			8,643		339
Total temporarily impaired securities	$	6,132	$	136	$	4,545	$	235		$	10,677	$	371
December 31, 2017
U.S. Treasury and other U.S. government agency securities	$	2,727	$	16	$	—	$	—		$	2,727	$	16
Residential mortgage-backed securities (a)	3,845		32		4,003		125			7,848		157
State and municipal securities (b)	—		—		5		—		(c)	5		—		(c)
Equity and other non-debt securities (b)	—		—		44		2			44		2
Total temporarily impaired securities	$	6,572	$	48	$	4,052	$	127		$	10,624	$	175


(a)	Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.


(b)	Primarily auction-rate securities.


(c)	Unrealized losses less than $0.5 million.

At September 30, 2018, the Corporation had 409 securities in an unrealized loss position with no credit impairment, including 19 U.S. Treasury securities and 390 residential mortgage-backed securities. The unrealized losses for these securities resulted from changes in market interest rates, not changes in credit quality. The Corporation ultimately expects full collection of the carrying amount of these securities, does not intend to sell the securities in an unrealized loss position, and it is not more-likely-than-not that the Corporation will be required to sell the securities in an unrealized loss position prior to recovery of amortized cost. The Corporation does not consider these securities to be other-than-temporarily impaired at September 30, 2018.

Sales, primarily from repositioning $1.3 billion of lower-yielding treasury securities, calls and write-downs of investment securities available-for-sale resulted in the following gains and losses recorded in “net securities losses” on the consolidated statements of comprehensive income, computed based on the adjusted cost of the specific security.



	Three Months Ended September 30,					Nine Months Ended September 30,
(in millions)	2018			2017		2018			2017
Securities gains	$	—		$	—	$	1		$	—
Securities losses	(20		)	—		(20		)	—
Net securities losses	$	(20	)	$	—	$	(19	)	$	—

The following table summarizes the amortized cost and fair values of debt securities by contractual maturity. Securities with multiple maturity dates are classified in the period of final maturity. Expected maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties.



(in millions)
September 30, 2018	Amortized Cost		Fair Value
Contractual maturity
Within one year	$	100	$	100
After one year through five years	2,993		2,958
After five years through ten years	1,634		1,598
After ten years	7,500		7,206
Total investment securities	$	12,227	$	11,862

Included in the contractual maturity distribution in the table above were residential mortgage-backed securities with total amortized cost of $9.5 billion and fair value of $9.2 billion. The actual cash flows of mortgage-backed securities may differ from contractual maturity as the borrowers of the underlying loans may exercise prepayment options.

At September 30, 2018, investment securities with a carrying value of $317 million were pledged where permitted or required by law to secure $224 million of liabilities, primarily public and other deposits of state and local government agencies as well as derivative instruments.