INVESTMENT SECURITIES

The following table presents the amortized cost and fair value of the investment securities portfolio as of the dates indicated:



($ in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
March 31, 2019
Securities available-for-sale:
SBA loan pool securities	$	831	$	—	$	(11	)	$	820
U.S. government agency and U.S. government sponsored enterprise residential mortgage-backed securities	448,956		18		(14,513		)	434,461
Non-agency residential mortgage-backed securities	319		12		—			331
Collateralized loan obligations	1,046,845		132		(11,286		)	1,035,691
Total securities available-for-sale	$	1,496,951	$	162	$	(25,810	)	$	1,471,303
December 31, 2018
Securities available-for-sale:
SBA loan pool securities	$	911	$	—	$	(1	)	$	910
U.S. government agency and U.S. government sponsored enterprise residential mortgage-backed securities	461,987		—		(24,545		)	437,442
Non-agency residential mortgage-backed securities	418		9		—			427
Non-agency commercial mortgage-backed securities	132,199		—		—			132,199
Collateralized loan obligations	1,431,171		141		(9,790		)	1,421,522
Total securities available-for-sale	$	2,026,686	$	150	$	(34,336	)	$	1,992,500

As of December 31, 2018, the Company changed its intent and decided to sell its non-agency commercial mortgage-backed securities in an unrealized loss position due to its strategy to reposition its securities profile and recognized $3.3 million of OTTI losses during the fourth quarter of 2018. During the three months ended March 31, 2019, the Company completed the sale of all remaining non-agency commercial mortgage-backed securities totaling $132.2 million resulting in a gain of $9 thousand. Additionally, during the three months ended March 31, 2019, the Company sold $365.3 million in collateralized loan obligations resulting in a gain of $143 thousand. During the three months ended March 31, 2018, the Company completed the sale of all remaining corporate debt securities, totaling $76.8 million resulting in a gain of $4.9 million, to reposition its securities available-for-sale portfolio.

At March 31, 2019, the Company's investment securities portfolio consisted of SBA loan pool securities, mortgage-backed securities, and collateralized loan obligations. The expected maturities of these types of securities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties.

At March 31, 2019 and December 31, 2018, there were no holdings of any one issuer, other than the U.S. Government and its agencies, in an amount greater than 10 percent of the Company's stockholders’ equity.

The following table presents proceeds from sales and calls of securities available-for-sale and the associated gross gains and losses realized through earnings upon the sales and calls of securities available-for-sale for the periods indicated:



	Three Months Ended March 31,
($ in thousands)	2019		2018
Gross realized gains on sales and calls of securities available-for-sale	$	208	$	5,241
Gross realized losses on sales and calls of securities available-for-sale	—		—
Net realized gains on sales and calls of securities available-for-sale	$	208	$	5,241
Proceeds from sales and calls of securities available-for-sale	$	521,684	$	287,517

Investment securities with carrying values of $107.3 million and $163.0 million as of March 31, 2019 and December 31, 2018, respectively, were pledged to secure FHLB advances, public deposits and for other purposes as required or permitted by law.

The following table summarizes the investment securities with unrealized losses by security type and length of time in a continuous unrealized loss position as of the dates indicated:



	Less Than 12 Months					12 Months or Longer					Total
($ in thousands)	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
March 31, 2019
Securities available-for-sale:
SBA loan pool securities	$	820	$	(11	)	$	—	$	—		$	820	$	(11	)
U.S. government agency and U.S. government sponsored enterprise residential mortgage-backed securities	200,351		(6,653		)	230,807		(7,860		)	431,158		(14,513		)
Non-agency residential mortgage-backed securities	15		—			7		—			22		—
Collateralized loan obligations	739,508		(10,437		)	195,301		(849		)	934,809		(11,286		)
Total securities available-for-sale	$	940,694	$	(17,101	)	$	426,115	$	(8,709	)	$	1,366,809	$	(25,810	)
December 31, 2018
Securities available-for-sale:
SBA loan pool securities	$	—	$	—		$	910	$	(1	)	$	910	$	(1	)
U.S. government agency and U.S. government sponsored enterprise residential mortgage-backed securities	13,494		(133		)	423,916		(24,412		)	437,410		(24,545		)
Non-agency residential mortgage-backed securities	90		—			16		—			106		—
Collateralized loan obligations	1,364,317		(9,480		)	32,790		(310		)	1,397,107		(9,790		)
Total securities available-for-sale	$	1,377,901	$	(9,613	)	$	457,632	$	(24,723	)	$	1,835,533	$	(34,336	)

The Company did not record other-than-temporary-impairment (OTTI) for investment securities for the three months ended March 31, 2019 or 2018.

At March 31, 2019, the Company’s securities available-for-sale portfolio consisted of 99 securities, 88 of which were in an unrealized loss position. At December 31, 2018, the Company’s securities available-for-sale portfolio consisted of 145 securities, 118 of which were in an unrealized loss position.

The Company monitors its securities portfolio to ensure it has adequate credit support. The majority of unrealized losses are related to the Company's mortgage-backed securities issued by U.S government sponsored entities and agencies. The Company also considers the lowest credit rating for identification of potential OTTI for other securities. As of March 31, 2019, nearly all of the Company's non-agency mortgage-backed securities or collateralized loan obligations investment securities in an unrealized loss position received an investment grade credit rating. The decline in fair value is attributable to changes in interest rates, and not credit quality. The Company believes there was no OTTI as of March 31, 2019 and does not have the intent to sell its securities in an unrealized loss position and further believes it is not likely that it will be required to sell these securities before their anticipated recovery.