Note 4 - Investment Securities

The amortized cost, gross unrealized gains and losses, and estimated fair values of investment securities available for sale at March 31, 2017 and December 31, 2016 are summarized below.



	March 31, 2017
(in thousands)	Amortized Cost		Gross Unrealized Gains	Gross Unrealized Losses		Fair Value
U.S. Treasury securities	$	83,441	—	(550	)	82,891
U.S. Government agency securities	12,089		342	—		12,431
Mortgage-backed securities issued by U.S. Government agencies	166,794		787	(1,302	)	166,279
Mortgage-backed securities issued by U.S. Government sponsored enterprises	2,837,359		3,779	(38,594	)	2,802,544
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	710,188		12	(13,308	)	696,892
State and municipal securities	1,800		1	—		1,801
Other investments	20,263		144	(303	)	20,104
Total investment securities available for sale	$	3,831,934	5,065	(54,057	)	3,782,942

	December 31, 2016
(in thousands)	Amortized Cost		Gross Unrealized Gains	Gross Unrealized Losses		Fair Value
U.S. Treasury securities	$	108,221	225	(644	)	107,802
U.S. Government agency securities	12,727		266	—		12,993
Mortgage-backed securities issued by U.S. Government agencies	174,440		1,116	(1,354	)	174,202
Mortgage-backed securities issued by U.S. Government sponsored enterprises	2,543,495		5,416	(42,571	)	2,506,340
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	905,789		1,214	(16,561	)	890,442
State and municipal securities	2,780		14	—		2,794
Equity securities	919		2,863	—		3,782
Other investments	20,247		—	(407	)	19,840
Total investment securities available for sale	$	3,768,618	11,114	(61,537	)	3,718,195

At March 31, 2017 and December 31, 2016, investment securities with a carrying value of $1.75 billion and $2.04 billion, respectively, were pledged to secure certain deposits and securities sold under repurchase agreements as required by law and contractual agreements.

Synovus has reviewed investment securities that are in an unrealized loss position as of March 31, 2017 and December 31, 2016 for OTTI and does not consider any securities in an unrealized loss position to be other-than-temporarily impaired. If Synovus intended to sell a security in an unrealized loss position, the entire unrealized loss would be reflected in earnings. Synovus does not intend to sell investment securities in an unrealized loss position prior to the recovery of the unrealized loss, which may be until maturity, and has the ability and intent to hold those securities for that period of time. Additionally, Synovus is not currently aware of any circumstances which will require it to sell any of the securities that are in an unrealized loss position prior to the respective securities' recovery of all such unrealized losses.

Declines in the fair value of available for sale securities below their cost that are deemed to have OTTI are reflected in earnings as realized losses to the extent the impairment is related to credit losses. The amount of the impairment related to other factors is recognized in other comprehensive income. Currently, unrealized losses on debt securities are attributable to increases in interest rates on comparable securities from the date of purchase. Synovus regularly evaluates its investment securities portfolio to ensure that there are no conditions that would indicate that unrealized losses represent OTTI. These factors include the length of time the security has been in a loss position, the extent that the fair value is below amortized cost, and the credit standing of the issuer. As of March 31, 2017, Synovus had 90 investment securities in a loss position for less than twelve months and four investment securities in a loss position for twelve months or longer.

Gross unrealized losses on investment securities and the fair value of the related securities, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position, at March 31, 2017 and December 31, 2016 are presented below.



	March 31, 2017
	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
U.S. Treasury securities	$	64,134	550	—	—	64,134	550
Mortgage-backed securities issued by U.S. Government agencies	123,299		1,185	3,497	117	126,796	1,302
Mortgage-backed securities issued by U.S. Government sponsored enterprises	2,155,464		38,594	—	—	2,155,464	38,594
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	641,126		12,420	23,723	888	664,849	13,308
Other investments	—		—	4,959	303	4,959	303
Total	$	2,984,023	52,749	32,179	1,308	3,016,202	54,057

	December 31, 2016
	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
U.S. Treasury securities	$	64,023	644	—	—	64,023	644
Mortgage-backed securities issued by U.S. Government agencies	128,121		1,240	3,626	114	131,747	1,354
Mortgage-backed securities issued by U.S. Government sponsored enterprises	2,123,181		42,571	—	—	2,123,181	42,571
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	682,492		15,653	24,801	908	707,293	16,561
Other investments	14,952		48	4,888	359	19,840	407
Total	$	3,012,769	60,156	33,315	1,381	3,046,084	61,537

The amortized cost and fair value by contractual maturity of investment securities available for sale at March 31, 2017 are shown below. The expected life of mortgage-backed securities or CMOs may differ from contractual maturities because issuers may have the right to call or prepay obligations with or without call or prepayment penalties. For purposes of the maturity table, mortgage-backed securities and CMOs, which are not due at a single maturity date, have been classified based on the final contractual maturity date.



	Distribution of Maturities at March 31, 2017
(in thousands)	Within One Year		1 to 5 Years	5 to 10 Years	More Than 10 Years	No Stated Maturity	Total
Amortized Cost
U.S. Treasury securities	$	18,756	64,685	—	—	—	83,441
U.S. Government agency securities	999		5,613	5,477	—	—	12,089
Mortgage-backed securities issued by U.S. Government agencies	—		—	33,513	133,281	—	166,794
Mortgage-backed securities issued by U.S. Government sponsored enterprises	93		1,603	570,250	2,265,413	—	2,837,359
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	—		—	—	710,188	—	710,188
State and municipal securities	1,620		180	—	—	—	1,800
Other investments	—		—	15,000	2,000	3,263	20,263
Total amortized cost	$	21,468	72,081	624,240	3,110,882	3,263	3,831,934

Fair Value
U.S. Treasury securities	$	18,756	64,135	—	—	—	82,891
U.S. Government agency securities	1,012		5,744	5,675	—	—	12,431
Mortgage-backed securities issued by U.S. Government agencies	—		—	33,728	132,551	—	166,279
Mortgage-backed securities issued by U.S. Government sponsored enterprises	96		1,700	565,770	2,234,978	—	2,802,544
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	—		—	—	696,892	—	696,892
State and municipal securities	1,620		181	—	—	—	1,801
Other investments	—		—	15,145	1,851	3,108	20,104
Total fair value	$	21,484	71,760	620,318	3,066,272	3,108	3,782,942

Proceeds from sales, gross gains, and gross losses on sales of securities available for sale for the three months ended March 31, 2017 and 2016 are presented below. The specific identification method is used to reclassify gains and losses out of other comprehensive income at the time of sale.



	Three Months Ended March 31,
(in thousands)	2017			2016
Proceeds from sales of investment securities available for sale	$	282,629		243,609
Gross realized gains on sales	7,702			954
Gross realized losses on sales	(34		)	(887	)
Investment securities gains, net	$	7,668		67