INVESTMENTS

The amortized cost and fair value of investment securities classified as available for sale and held to maturity at December 31, 2018 and 2017, were as follows:



	December 31, 2018
(Dollars in thousands)	Cost		Gross unrealized gains		Gross unrealized losses		Fair value
Investment securities available for sale
U.S. Treasury	$	1,249,243	$	633	$	2,166	$	1,247,710
Government agency	257,252		222		639		256,835
Mortgage-backed securities	2,956,793		5,309		52,763		2,909,339
Corporate bonds	139,906		59		864		139,101
Other	3,923		202		—		4,125
Total investment securities available for sale	$	4,607,117	$	6,425	$	56,432	$	4,557,110

	December 31, 2017
	Cost		Gross unrealized gains		Gross unrealized losses		Fair value
U.S. Treasury	$	1,658,410	$	—	$	546	$	1,657,864
Government agency	8,695		15		40		8,670
Mortgage-backed securities	5,419,379		1,529		80,152		5,340,756
Marketable equity securities	75,471		29,737		—		105,208
Corporate bonds	59,414		557		8		59,963
Other	7,645		256		182		7,719
Total investment securities available for sale	$	7,229,014	$	32,094	$	80,928	$	7,180,180

	December 31, 2018
	Cost		Gross unrealized gains		Gross unrealized losses		Fair value
Investment securities held to maturity
Mortgage-backed securities	$	2,184,653	$	17,339	$	490	$	2,201,502

	December 31, 2017
	Cost		Gross unrealized gains		Gross unrealized losses		Fair value
Mortgage-backed securities	$	76	$	5	$	—	$	81

The adoption of ASU 2016-01in the first quarter of 2018 resulted in marketable equity investments being reported separately in the Consolidated Balance Sheets and the change in fair value of those investments is reflected in the Consolidated Statements of Income. At adoption, we recorded a cumulative-effect adjustment to the consolidated balance sheet resulting in an $18.7 million increase to retained earnings and a corresponding decrease to AOCI. The fair value of marketable equity securities was $92.6 million and $105.2 million, respectively, at December 31, 2018 and 2017.

On May 1, 2018, mortgage-backed securities with an amortized cost of $2.49 billion were transferred from investments available for sale to the held to maturity portfolio. At the time of transfer, the mortgage-backed securities had a fair value of $2.38 billion and a weighted average contractual maturity of 13 years. The unrealized loss on these securities at the date of transfer was $109.5 million or $84.3 million net of tax, and continues to be reported as a component of AOCI. This unrealized loss will be accreted over the remaining expected life of the securities as an adjustment of yield and is partially offset by the amortization of the corresponding discount on the transferred securities. As of December 31, 2018, $17.1 million or $13.2 million net of tax, of the unrealized loss has been accreted from AOCI into interest income. FCB has the intent and ability to retain these securities until maturity.

Investments in mortgage-backed securities represent securities issued by the Government National Mortgage Association, Federal National Mortgage Association and Federal Home Loan Mortgage Corporation. Investments in government agency securities represent securities issued by the United States Small Business Administration. Investments in corporate bonds and marketable equity securities represent positions in securities of other financial institutions.

Other investments include trust preferred securities of financial institutions. BancShares holds approximately 298,000 shares of Visa Class B common stock with a cost basis of zero. BancShares' Visa Class B shares are not considered to have a readily determinable fair value and are included in the Consolidated Balance Sheets at a $0 fair value.

The following table provides the amortized cost and fair value by contractual maturity. Expected maturities will differ from contractual maturities on certain securities because borrowers and issuers may have the right to call or prepay obligations with or without prepayment penalties. Mortgage-backed, government agency and equity securities are stated separately as they are not due at a single maturity date.



	December 31, 2018				December 31, 2017
(Dollars in thousands)	Cost		Fair value		Cost		Fair value
Investment securities available for sale
Non-amortizing securities maturing in:
One year or less	$	1,049,253	$	1,047,380	$	808,768	$	808,301
One through five years	205,526		205,805		849,642		849,563
Five through 10 years	134,370		133,626		59,414		59,963
Over 10 years	3,923		4,125		7,645		7,719
Government agency	257,252		256,835		8,695		8,670
Mortgage-backed securities	2,956,793		2,909,339		5,419,379		5,340,756
Marketable equity securities	—		—		75,471		105,208
Total investment securities available for sale	$	4,607,117	$	4,557,110	$	7,229,014	$	7,180,180
Investment securities held to maturity
Mortgage-backed securities held to maturity	$	2,184,653	$	2,201,502	$	76	$	81

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



	Year ended December 31
(Dollars in thousands)	2018			2017			2016
Gross gains on retirement/sales of investment securities available for sale	$	353		$	11,635		$	27,104
Gross losses on sales of investment securities available for sale	(2		)	(7,342		)	(431		)
Net securities gains	$	351		$	4,293		$	26,673

The following table provides the realized and unrealized gains or losses on marketable equity securities for the three and twelve months ended December 31, 2018.



(Dollars in thousands)	Three months ended December 31, 2018			Twelve months ended December 31, 2018
Marketable equity securities (losses) gains, net	$	(16,875	)	$	(7,610	)
Less net gains recognized on marketable equity securities sold	9			1,190
Unrealized (losses) gains recognized on marketable equity securities held	$	(16,884	)	$	(8,800	)

The following table provides information regarding securities with unrealized losses as of December 31, 2018 and 2017:



	December 31, 2018
	Less than 12 months				12 months or more				Total
(Dollars in thousands)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Investment securities available for sale:
U.S. Treasury	$	248,983	$	113	$	848,622	$	2,053	$	1,097,605	$	2,166
Government agency	115,273		601		2,310		38		117,583		639
Mortgage-backed securities	262,204		2,387		1,940,695		50,376		2,202,899		52,763
Corporate bonds	79,066		842		5,000		22		84,066		864
Total	$	705,526	$	3,943	$	2,796,627	$	52,489	$	3,502,153	$	56,432
Investment securities held to maturity:
Mortgage-backed securities	$	5,111	$	181	$	10,131	$	309	$	15,242	$	490

	December 31, 2017
	Less than 12 months				12 months or more				Total
	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Investment securities available for sale:
U.S. Treasury	$	1,408,166	$	345	$	249,698	$	201	$	1,657,864	$	546
Government agency	848		12		2,527		28		3,375		40
Mortgage-backed securities	2,333,254		20,911		2,723,406		59,241		5,056,660		80,152
Corporate bonds	5,025		8		—		—		5,025		8
Other	5,349		182		—		—		5,349		182
Total	$	3,752,642	$	21,458	$	2,975,631	$	59,470	$	6,728,273	$	80,928

As of December 31, 2018, there were 221 investment securities available for sale that had continuous losses for more than 12 months of which 213 are government sponsored, enterprise-issued mortgage-backed securities or government agency securities, 7 are U.S. Treasury securities and 1 is a corporate bond. There were 2 investment securities held to maturity, which were government sponsored, enterprise-issued mortgage securities, that had continuous losses for more than 12 months at December 31, 2018.

None of the unrealized losses identified as of December 31, 2018 or December 31, 2017 relate to the marketability of the securities or the issuer’s ability to honor redemption obligations. Rather, the unrealized losses related to changes in interest rates and spreads relative to when the investment securities were purchased. BancShares has 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 OTTI.

Debt securities having an aggregate carrying value of $4.03 billion at December 31, 2018 and $4.59 billion at December 31, 2017, were pledged as collateral to secure public funds on deposit and certain short-term borrowings, and for other purposes as required by law.