The following table sets forth certain information regarding the amortized cost basis and fair values of our investment securities AFS and held-to-maturity ("HTM"):


	At March 31, 2022
(in thousands)	Amortized cost		Gross unrealized gains		Gross unrealized losses		Fair value

AFS
Mortgage backed securities ("MBS"):
Residential	$	30,689	$	6	$	(1,508)	$	29,187
Commercial	70,312		38		(3,958)		66,392
Collateralized mortgage obligations ("CMOs"):
Residential	276,246		186		(9,940)		266,492
Commercial	138,168		135		(3,424)		134,879
Municipal bonds	535,353		2,802		(23,016)		515,139
Corporate debt securities	26,850		97		(574)		26,373
U.S. Treasury securities	23,263		—		(1,541)		21,722

Total	$	1,100,881	$	3,264	$	(43,961)	$	1,060,184

HTM




Municipal bonds	$	4,143	$	8	$	(17)	$	4,134


	At December 31, 2021
(in thousands)	Amortized cost		Gross unrealized gains		Gross unrealized losses		Fair value

AFS
MBS:
Residential	$	32,905	$	396	$	(338)	$	32,963
Commercial	62,094		933		(235)		62,792
CMOs:
Residential	186,703		2,012		(1,321)		187,394
Commercial	135,102		1,890		(333)		136,659
Municipal bonds	516,693		24,154		(924)		539,923
Corporate debt securities	18,918		699		(1)		19,616
U.S. Treasury securities	23,348		—		(173)		23,175

Total	$	975,763	$	30,084	$	(3,325)	$	1,002,522

HTM




Municipal bonds	$	4,169	$	136	$	—	$	4,305

At March 31, 2022, the Company held $19 million of trading securities, consisting of US Treasury notes used as economic hedges of our mortgage servicing rights, which are carried at fair value and included as investment securities on the balance sheet. Unrealized losses on trading securities, which are included in loan servicing income, were $0.7 million in the quarter ended March 31, 2022.

MBS and CMOs represent securities issued by government sponsored enterprises ("GSEs"). Most of the MBS and CMO securities in our investment portfolio are guaranteed by Fannie Mae, Ginnie Mae or Freddie Mac. Municipal bonds are comprised of general obligation bonds (i.e., backed by the general credit of the issuer) and revenue bonds (i.e., backed by either collateral or revenues from the specific project being financed) issued by various municipal corporations. As of March 31, 2022

and December 31, 2021, all securities held, including municipal bonds and corporate debt securities, were rated investment grade, based upon external ratings where available and, where not available, based upon internal ratings which correspond to ratings as defined by Standard and Poor's Rating Services or Moody's Investors Services.

Investment securities AFS that were in an unrealized loss position are presented in the following tables based on the length of time the individual securities have been in an unrealized loss position:


	At March 31, 2022
	Less than 12 months				12 months or more				Total
(in thousands)	Gross unrealized losses		Fair value		Gross unrealized losses		Fair value		Gross unrealized losses		Fair value


AFS
MBS:
Residential	$	(1,064)	$	25,716	$	(444)	$	2,233	$	(1,508)	$	27,949
Commercial	(3,958)		58,243		—		—		(3,958)		58,243
CMOs:
Residential	(7,475)		177,481		(2,465)		21,315		(9,940)		198,796
Commercial	(2,802)		103,919		(622)		7,608		(3,424)		111,527
Municipal bonds	(21,126)		375,801		(1,890)		12,141		(23,016)		387,942
Corporate debt securities	(574)		16,758		—		—		(574)		16,758
U.S. Treasury securities	(1,541)		21,723		—		—		(1,541)		21,723

Total	$	(38,540)	$	779,641	$	(5,421)	$	43,297	$	(43,961)	$	822,938
HTM




Municipal bonds	$	(17)	$	2,474	$	—	$	—	$	(17)	$	2,474


	At December 31, 2021
	Less than 12 months				12 months or more				Total
(in thousands)	Gross unrealized losses		Fair value		Gross unrealized losses		Fair value		Gross unrealized losses		Fair value


MBS:
Residential	$	(38)	$	5,324	$	(300)	$	2,406	$	(338)	$	7,730
Commercial	(235)		18,127		—		—		(235)		18,127
CMOs:
Residential	(1,007)		53,068		(314)		7,116		(1,321)		60,184
Commercial	(135)		14,806		(198)		5,132		(333)		19,938
Municipal bonds	(914)		64,237		(10)		1,058		(924)		65,295
Corporate debt securities	(1)		3,164		—		—		(1)		3,164
U.S. Treasury securities	(173)		23,175		—		—		(173)		23,175

Total	$	(2,503)	$	181,901	$	(822)	$	15,712	$	(3,325)	$	197,613

The Company has evaluated AFS securities that are in an unrealized loss position and has determined that the decline in value is temporary and is related to the change in market interest rates since purchase. The decline in value is not related to any issuer- or industry-specific credit event. The Company has not identified any expected credit losses on its debt securities as of March 31, 2022 or December 31, 2021. In addition, as of March 31, 2022 and December 31, 2021, the Company had not made a decision to sell any of its debt securities held, nor did the Company consider it more likely than not that it would be required to sell such securities before recovery of their amortized cost basis.


	At March 31, 2022
	Within one year				After one year through five years				After five years through ten years				After ten years				Total
(dollars in thousands)	Fair Value		Weighted Average Yield		Fair Value		Weighted Average Yield		Fair Value		Weighted Average Yield		Fair Value		Weighted Average Yield		Fair Value		Weighted Average Yield

AFS






Municipal bonds	$	4,159	3.57	%	$	13,675	3.23	%	$	66,619	3.40	%	$	430,686	3.03	%	$	515,139	3.09	%
Corporate debt securities	—		—	%	5,573		3.54	%	20,800		4.39	%	—		—	%	26,373		4.22	%
U.S. Treasury securities	—		—	%	—		—	%	21,722		1.20	%	—		—	%	21,722		1.20	%

Total	$	4,159	3.57	%	$	19,248	3.32	%	$	109,141	3.13	%	$	430,686	3.03	%	$	563,234	3.07	%

HTM




Municipal bonds	$	1,659	2.91	%	$	2,475	2.07	%	$	—	—	%	$	—	—	%	$	4,134	2.41	%


	At December 31, 2021
	Within one year				After one year through five years				After five years through ten years				After ten years				Total
(dollars in thousands)	Fair Value		Weighted Average Yield		Fair Value		Weighted Average Yield		Fair Value		Weighted Average Yield		Fair Value		Weighted Average Yield		Fair Value		Weighted Average Yield







AFS
Municipal bonds	$	4,933	3.79	%	$	14,366	3.26	%	$	68,025	3.60	%	$	452,599	3.23	%	$	539,923	3.28	%
Corporate debt securities	—		—	%	6,563		3.60	%	13,053		5.03	%	—		—	%	19,616		4.55	%
U.S. Treasury securities	—		—	%	—		—	%	23,175		1.27	%	—		—	%	23,175		1.27	%

Total	$	4,933	3.79	%	$	20,929	3.37	%	$	104,253	3.23	%	$	452,599	3.23	%	$	582,714	3.24	%

HTM




Municipal bonds	$	1,684	2.86	%	$	2,621	2.12	%	$	—	—	%	$	—	—	%	$	4,305	2.42	%

The weighted-average yield is computed using the contractual coupon of each security weighted based on the fair value of each security and does not include adjustments to a tax equivalent basis. MBS and CMOs are excluded from the tables above because such securities are not due on a single maturity date. The weighted average yield of MBS and CMOs as of March 31, 2022 and December 31, 2021 was 1.88% and 1.82%, respectively.

The following table summarizes the carrying value of securities pledged as collateral to secure public deposits, borrowings and other purposes as permitted or required by law:


(in thousands)	At March 31, 2022		At December 31, 2021


Washington, Oregon and California State to secure public deposits	$	201,444	$	206,153

Other securities pledged	4,972		5,258
Total securities pledged as collateral	$	206,416	$	211,411

The Company assesses the creditworthiness of the counterparties that hold the pledged collateral and has determined that these arrangements have little credit risk.