Note 4 - Investment Securities Available for Sale

The amortized cost, gross unrealized gains and losses, and estimated fair values of investment securities available for sale at March 31, 2018 and December 31, 2017 are summarized below.



	March 31, 2018
(in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
U.S. Treasury securities	$	122,655	$	—	$	(1,724	)	$	120,931
U.S. Government agency securities	10,769		128		—			10,897
Mortgage-backed securities issued by U.S. Government agencies	115,888		237		(3,257		)	112,868
Mortgage-backed securities issued by U.S. Government sponsored enterprises	2,734,650		483		(71,133		)	2,664,000
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	1,102,361		—		(37,320		)	1,065,041
State and municipal securities	115		—		—			115
Corporate debt and other debt securities	17,000		274		(148		)	17,126
Total investment securities available for sale	$	4,103,438	$	1,122	$	(113,582	)	$	3,990,978

	December 31, 2017
(in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
U.S. Treasury securities	$	83,608	$	—	$	(934	)	$	82,674
U.S. Government agency securities	10,771		91		—			10,862
Mortgage-backed securities issued by U.S. Government agencies	121,283		519		(1,362		)	120,440
Mortgage-backed securities issued by U.S. Government sponsored enterprises	2,666,818		5,059		(31,354		)	2,640,523
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	1,135,259		144		(23,404		)	1,111,999
State and municipal securities	180		—		—			180
Corporate debt and other securities	20,320		294		(223		)	20,391
Total investment securities available for sale	$	4,038,239	$	6,107	$	(57,277	)	$	3,987,069

At March 31, 2018 and December 31, 2017, investment securities with a carrying value of $1.01 billion and $2.00 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, 2018 and December 31, 2017 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 not 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, 2018, Synovus had 75 investment securities in a loss position for less than twelve months and 54 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, 2018 and December 31, 2017 are presented below.



	March 31, 2018
	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	$	72,694	$	989	$	29,313	$	735	$	102,007	$	1,724
Mortgage-backed securities issued by U.S. Government agencies	39,763		1,045		52,763		2,212		92,526		3,257
Mortgage-backed securities issued by U.S. Government sponsored enterprises	1,656,562		38,195		882,984		32,938		2,539,546		71,133
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	629,793		17,650		435,247		19,670		1,065,040		37,320
Corporate debt and other debt securities	—		—		1,852		148		1,852		148
Total	$	2,398,812	$	57,879	$	1,402,159	$	55,703	$	3,800,971	$	113,582

	December 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	$	34,243	$	443	$	29,562	$	491	$	63,805	$	934
Mortgage-backed securities issued by U.S. Government agencies	36,810		357		55,740		1,005		92,550		1,362
Mortgage-backed securities issued by U.S. Government sponsored enterprises	1,271,012		10,263		929,223		21,091		2,200,235		31,354
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	653,781		9,497		426,237		13,907		1,080,018		23,404
Corporate debt and other securities	—		—		5,097		223		5,097		223
Total	$	1,995,846	$	20,560	$	1,445,859	$	36,717	$	3,441,705	$	57,277

The amortized cost and fair value by contractual maturity of investment securities available for sale at March 31, 2018 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, 2018
(in thousands)	Within One Year		1 to 5 Years		5 to 10 Years		More Than 10 Years		Total
Amortized Cost
U.S. Treasury securities	$	18,924	$	103,731	$	—	$	—	$	122,655
U.S. Government agency securities	2,330		6,437		2,002		—		10,769
Mortgage-backed securities issued by U.S. Government agencies	—		—		29,355		86,533		115,888
Mortgage-backed securities issued by U.S. Government sponsored enterprises	7		1,657		578,774		2,154,212		2,734,650
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	—		—		18,652		1,083,709		1,102,361
State and municipal securities	115		—		—		—		115
Corporate debt and other debt securities	—		—		15,000		2,000		17,000
Total amortized cost	$	21,376	$	111,825	$	643,783	$	3,326,454	$	4,103,438

Fair Value
U.S. Treasury securities	$	18,924	$	102,007	$	—	$	—	$	120,931
U.S. Government agency securities	2,355		6,514		2,028		—		10,897
Mortgage-backed securities issued by U.S. Government agencies	—		—		28,993		83,875		112,868
Mortgage-backed securities issued by U.S. Government sponsored enterprises	7		1,723		565,331		2,096,939		2,664,000
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises	—		—		18,218		1,046,823		1,065,041
State and municipal securities	115		—		—		—		115
Corporate debt and other debt securities	—		—		15,274		1,852		17,126
Total fair value	$	21,401	$	110,244	$	629,844	$	3,229,489	$	3,990,978

Synovus did not sell any securities available for sale during the three months ended March 31, 2018. Proceeds from sales, gross gains, and gross losses on sales of securities available for sale for the three months ended March 31, 2017 are presented below. The specific identification method is used to reclassify gains and losses out of other comprehensive income at the time of sale. On January 1, 2018, Synovus transferred $3.2 million, at fair value, from investment securities available for sale to other assets upon adoption of ASU 2016-01.



	Three Months Ended March 31,
(in thousands)	2018		2017
Proceeds from sales of investment securities available for sale	$	—	$	282,629
Gross realized gains on sales	—		7,702
Gross realized losses on sales	—		(34		)
Investment securities gains, net	$	—	$	7,668