Investments

The amortized cost and fair value of securities available for sale are as follows:



	December 31, 2018
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Available for sale:
Mortgage-backed securities	$	159,937	$	155	$	(5,517	)	$	154,575
Utah Housing Corporation bonds	22,388		23		(741		)	21,670
Total	$	182,325	$	178	$	(6,258	)	$	176,245

	December 31, 2017
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Available for sale:
Mortgage-backed securities	$	227,607	$	650	$	(3,210	)	$	225,047
Utah Housing Corporation bonds	20,000		—		(959		)	19,041
Total	$	247,607	$	650	$	(4,169	)	$	244,088

The following table summarizes the amount of gross unrealized losses for our mortgage-backed securities and Utah Housing Corporation bonds and the estimated fair value for securities having gross unrealized loss positions, categorized by length of time the securities have been in an unrealized loss position:



	Less than 12 months					12 months or more					Total
	Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value
As of December 31, 2018:
Mortgage-backed securities	$	(228	)	$	16,948	$	(5,289	)	$	125,537	$	(5,517	)	$	142,485
Utah Housing Corporation bonds	—			—		(741		)	16,647		(741		)	16,647
Total	$	(228	)	$	16,948	$	(6,030	)	$	142,184	$	(6,258	)	$	159,132

As of December 31, 2017:
Mortgage-backed securities	$	(772	)	$	77,356	$	(2,438	)	$	110,500	$	(3,210	)	$	187,856
Utah Housing Corporation bonds	(77		)	4,923		(882		)	14,118		(959		)	19,041
Total	$	(849	)	$	82,279	$	(3,320	)	$	124,618	$	(4,169	)	$	206,897

Our investment portfolio is comprised primarily of mortgage-backed securities issued by Ginnie Mae, Fannie Mae and Freddie Mac, with amortized costs of $64 million, $46 million, and $50 million, respectively, at December 31, 2018. We own these securities to meet our requirements under the Community Reinvestment Act. In the second quarter of 2018, we elected to sell nine securities totaling $41 million to better align the portfolio with the Community Reinvestment Act requirements, and we recognized a $2 million loss upon the sale of those securities. As of December 31, 2018, there were 74 of 86 separate mortgage-backed securities with unrealized losses in our investment portfolio, and 34 of the 74 securities in a net loss position were issued under Ginnie Mae programs that carry a full faith and credit guarantee from the U.S. Government. The remaining securities in a net loss position carry a principal and interest guarantee by Fannie Mae or Freddie Mac, respectively. We have the intent and ability to hold these bonds for a period of time sufficient for the market price to recover to at least the adjusted amortized cost of the security. As of December 31, 2017, there were 62 of 92 separate mortgage-backed securities with unrealized losses in our investment portfolio, and 31 of the 62 securities in a net loss position were issued under Ginnie Mae programs that carry a full faith and credit guarantee from the U.S. Government. The remainder carried a principal and interest guarantee by Fannie Mae or Freddie Mac, respectively.

We also invest in Utah Housing Corporation bonds for the purpose of complying with the Community Reinvestment Act. These bonds are Aa3 rated by Moody’s Investors Service. The amortized cost of the investment on the consolidated balance sheet at December 31, 2018 and December 31, 2017 was $22 million and $20 million, respectively. We have the intent and ability to hold these bonds for a period of time sufficient for the market price to recover to at least the adjusted amortized cost of the security.

As of December 31, 2018, the amortized cost and fair value of securities, by contractual maturities, are summarized below. Contractual maturities versus actual maturities may differ due to the effect of prepayments.



Year of Maturity	Amortized Cost		Estimated Fair Value
2038	$	265	$	279
2039	2,963		3,060
2042	8,689		8,156
2043	14,192		13,779
2044	22,132		21,556
2045	23,918		23,005
2046	37,939		36,290
2047	56,376		54,216
2048	15,851		15,904
Total	$	182,325	$	176,245

The mortgage-backed securities have been pledged to the FRB as collateral against any advances and accrued interest under the Primary Credit lending program sponsored by the FRB. We had $147 million and $218 million par value of mortgage-backed securities pledged to this borrowing facility at December 31, 2018 and 2017, respectively, as discussed further in Note 9, “Borrowings.”