The amortized cost, gross unrealized gains and losses, allowance for credit losses and fair value of AFS securities as of March 31, 2022 and December 31, 2021 were as follows:


	As of March 31, 2022
	Amortized Cost		Unrealized Gains		Unrealized Losses		Allowance for Credit Losses		Fair Value
	(In thousands)
Debt securities:
Government-sponsored residential mortgage-backed securities	$	5,329,748	$	264	$	(360,666)	$	—	$	4,969,346
Government-sponsored commercial mortgage-backed securities	1,707,131		—		(91,204)		—		1,615,927
U.S. Agency bonds	1,099,916		—		(86,017)		—		1,013,899
U.S. Treasury securities	59,458		—		(3,223)		—		56,235
State and municipal bonds and obligations	258,769		2,792		(1,245)		—		260,316
Other debt securities	1,598		—		(16)		—		1,582
	$	8,456,620	$	3,056	$	(542,371)	$	—	$	7,917,305


	As of December 31, 2021
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
	(In thousands)
Debt securities:
Government-sponsored residential mortgage-backed securities	$	5,577,292	$	17,918	$	(70,502)	$	5,524,708
Government-sponsored commercial mortgage-backed securities	1,420,748		760		(12,640)		1,408,868
U.S. Agency bonds	1,202,377		1,067		(28,430)		1,175,014
U.S. Treasury securities	89,434		5		(834)		88,605
State and municipal bonds and obligations	263,910		16,460		(41)		280,329
Small business administration pooled securities	31,821		282		—		32,103
Other debt securities	1,597		—		—		1,597
	$	8,587,179	$	36,492	$	(112,447)	$	8,511,224

The Company did not record a provision for credit losses on any AFS securities for the three months ended March 31, 2022. Accrued interest receivable on AFS securities totaled $13.8 million and $14.3 million as of March 31, 2022 and December 31, 2021, respectively, and is included within other assets on the consolidated balance sheets. The Company did not record any write-offs of accrued interest income on AFS securities during the three months ended March 31, 2022. No securities held by the Company were delinquent on contractual payments as of March 31, 2022, nor were any securities placed on non-accrual status for the period then ended.

Gross realized gains from sales of AFS securities during the three months ended March 31, 2022 and 2021 were $1.0 million and $1.2 million, respectively. Gross realized losses from sales of AFS securities during the three months ended March 31, 2022 were $3.2 million. The Company had no significant gross realized losses from sales of AFS securities during the three months ended March 31, 2021. There was no OTTI recorded during the three months ended March 31, 2021.

Prior to the Company’s adoption of ASU 2016-13, management prepared an estimate of the Company’s expected cash flows for AFS investment securities that potentially may be deemed to have been an OTTI. This estimate began with the contractual cash flows of the security which was then reduced by an estimate of probable credit losses associated with the security. When estimating the extent of probable losses on the securities, management considered the credit quality and the ability to pay of the underlying issuers. Indicators of diminished credit quality of the issuers included defaults, interest deferrals, or “payments in kind.” Management also considered those factors listed in the “Investments – Debt and Equity Securities” topic of the FASB ASC when estimating the ultimate realizability of the cash flows for each individual security.

The resulting estimate of expected cash flows after considering credit was then subject to a present value computation using a discount rate equal to the current yield used to accrete the beneficial interest or the effective interest rate implicit in the security at the date of acquisition. If the present value of the estimated expected cash flows was less than the current amortized cost basis, an OTTI was considered to have occurred and the security was written down to the fair value indicated by the cash flow analysis. As part of the analysis, management considered whether it intended to sell the security or whether it was more than likely that it would be required to sell the security before the expected recovery of its amortized cost basis.

Information pertaining to AFS securities with gross unrealized losses as of March 31, 2022, for which the Company did not recognize a provision for credit losses under CECL, and as of December 31, 2021, for which the Company did not deem to be OTTI under its prior methodology, aggregated by investment category and length of time that individual securities had been in a continuous loss position, follows:


	As of March 31, 2022
		Less than 12 Months				12 Months or Longer				Total
	# of Holdings	Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value
	(Dollars in thousands)
Government-sponsored residential mortgage-backed securities	322	$	223,347	$	3,513,073	$	137,319	$	1,403,234	$	360,666	$	4,916,307
Government-sponsored commercial mortgage-backed securities	205	85,425		1,548,080		5,779		67,847		91,204		1,615,927
U.S. Agency bonds	37	12,573		226,708		73,444		787,191		86,017		1,013,899
U.S. Treasury securities	2	3,223		56,235		—		—		3,223		56,235
State and municipal bonds and obligations	103	1,245		82,709		—		—		1,245		82,709
Other debt securities	3	16		1,582		—		—		16		1,582
	672	$	325,829	$	5,428,387	$	216,542	$	2,258,272	$	542,371	$	7,686,659


	As of December 31, 2021
		Less than 12 Months				12 Months or Longer				Total
	# of Holdings	Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value
	(Dollars in thousands)
Government-sponsored residential mortgage-backed securities	264	$	70,502	$	4,615,457	$	—	$	—	$	70,502	$	4,615,457
Government-sponsored commercial mortgage-backed securities	165	12,218		1,102,444		422		15,682		12,640		1,118,126
U.S. Agency bonds	27	2,169		191,222		26,261		794,353		28,430		985,575
U.S. Treasury securities	3	834		78,588		—		—		834		78,588
State and municipal bonds and obligations	11	41		5,436		—		—		41		5,436
	470	$	85,764	$	5,993,147	$	26,683	$	810,035	$	112,447	$	6,803,182

The Company does not intend to sell these investments and has determined based upon available evidence that it is more likely than not that the Company will not be required to sell each security before the expected recovery of its amortized cost basis. As a result, the Company did not recognize a provision for credit losses on these investments as of March 31, 2022. As it relates to securities with gross unrealized losses as of December 31, 2021, the Company did not consider these investments to be OTTI under its prior methodology. The Company made this determination by reviewing various qualitative and quantitative factors regarding each investment category, such as current market conditions, extent and nature of changes in fair value, issuer rating changes and trends, and volatility of earnings.

•Government-sponsored residential mortgage-backed securities – The securities with unrealized losses in this portfolio have contractual terms that generally do not permit the issuer to settle the security at a price less than the current par value of the investment. The decline in market value of these securities is attributable to changes in interest rates and not credit quality. Additionally, these securities are implicitly guaranteed by the U.S. government or one of its agencies.

•Government-sponsored commercial mortgage-backed securities – The securities with unrealized losses in this portfolio have contractual terms that generally do not permit the issuer to settle the security at a price less than the current par value of the investment. The decline in market value of these securities is attributable to

•U.S. Agency bonds – The securities with unrealized losses in this portfolio have contractual terms that generally do not permit the issuer to settle the security at a price less than the current par value of the investment. The decline in market value of these securities is attributable to changes in interest rates and not credit quality. Additionally, these securities are implicitly guaranteed by the U.S. government or one of its agencies.

•U.S. Treasury securities – The securities with unrealized losses in this portfolio have contractual terms that generally do not permit the issuer to settle the security at a price less than the current par value of the investment. The decline in market value of these securities is attributable to changes in interest rates and not credit quality. Additionally, these securities are implicitly guaranteed by the U.S. government.

•State and municipal bonds and obligations – The securities with unrealized losses in this portfolio have contractual terms that generally do not permit the issuer to settle the security at a price less than the current par value of the investment. The decline in market value of these securities is attributable to changes in interest rates and not credit quality.


	As of March 31, 2022
	Amortized Cost		Unrealized Gains		Unrealized Losses		Allowance for Credit Losses		Fair Value
	(In thousands)
Debt securities:
Government-sponsored residential mortgage-backed securities	$	192,231	$	—	$	(3,318)	$	—	$	188,913
Government-sponsored commercial mortgage-backed securities	203,203		17		(10)		—		203,210
	$	395,434	$	17	$	(3,328)	$	—	$	392,123

The Company did not record a provision for estimated credit losses on any HTM securities for the three months ended March 31, 2022. Accrued interest receivable on HTM securities totaled $0.8 million as of March 31, 2022 and is included within other assets on the consolidated balance sheets. The Company did not record any write-offs of accrued interest income on HTM securities during the three months ended March 31, 2022. No securities held by the Company were delinquent on contractual payments as of March 31, 2022, nor were any securities placed on non-accrual status for the period then ended.

The amortized cost and estimated fair value of AFS and HTM securities by contractual maturities as of March 31, 2022 and December 31, 2021 are shown below. Actual maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without prepayment penalties.


	As of March 31, 2022
	Due in one year or less				Due after one year to five years				Due after five to ten years				Due after ten years				Total
	Amortized Cost		Fair Value		Amortized Cost		Fair Value		Amortized Cost		Fair Value		Amortized Cost		Fair Value		Amortized Cost		Fair Value
	(In thousands)
Available for sale securities
Government-sponsored residential mortgage-backed securities	$	1	$	1	$	20,992	$	21,143	$	832,510	$	790,125	$	4,476,245	$	4,158,077	$	5,329,748	$	4,969,346
Government-sponsored commercial mortgage-backed securities	—		—		190,509		182,639		700,994		658,732		815,628		774,556		1,707,131		1,615,927
U.S. Agency bonds	—		—		578,810		537,301		521,106		476,598		—		—		1,099,916		1,013,899
U.S. Treasury securities	10,000		9,955		49,458		46,280		—		—		—		—		59,458		56,235
State and municipal bonds and obligations	4,659		4,653		36,766		36,723		68,574		68,850		148,770		150,090		258,769		260,316
Other debt securities	300		299		1,298		1,283		—		—		—		—		1,598		1,582
Total available for sale securities	14,960		14,908		877,833		825,369		2,123,184		1,994,305		5,440,643		5,082,723		8,456,620		7,917,305
Held to maturity securities
Government-sponsored residential mortgage-backed securities	—		—		—		—		—		—		192,231		188,913		192,231		188,913
Government-sponsored commercial mortgage-backed securities	—		—		—		—		203,203		203,210		—		—		203,203		203,210
Total held to maturity securities	—		—		—		—		203,203		203,210		192,231		188,913		395,434		392,123
Total	$	14,960	$	14,908	$	877,833	$	825,369	$	2,326,387	$	2,197,515	$	5,632,874	$	5,271,636	$	8,852,054	$	8,309,428


	As of December 31, 2021
	Due in one year or less				Due after one year to five years				Due after five to ten years				Due after ten years				Total
	Amortized Cost		Fair Value		Amortized Cost		Fair Value		Amortized Cost		Fair Value		Amortized Cost		Fair Value		Amortized Cost		Fair Value
	(In thousands)
Available for sale securities
Government-sponsored residential mortgage-backed securities	$	—	$	—	$	24,935	$	25,962	$	899,169	$	892,029	$	4,653,188	$	4,606,717	$	5,577,292	$	5,524,708
Government-sponsored commercial mortgage-backed securities	—		—		139,095		137,755		387,177		378,414		894,476		892,699		1,420,748		1,408,868
U.S. Agency bonds	5,508		5,515		531,821		520,935		665,048		648,564		—		—		1,202,377		1,175,014
U.S. Treasury securities	40,010		40,001		49,424		48,604		—		—		—		—		89,434		88,605
State and municipal bonds and obligations	6,137		6,116		33,692		34,704		72,226		75,416		151,855		164,093		263,910		280,329
Small Business Administration pooled securities	—		—		4,062		4,092		—		—		27,759		28,011		31,821		32,103
Other debt securities	300		300		1,297		1,297		—		—		—		—		1,597		1,597
Total	$	51,955	$	51,932	$	784,326	$	773,349	$	2,023,620	$	1,994,423	$	5,727,278	$	5,691,520	$	8,587,179	$	8,511,224

As of March 31, 2022 and December 31, 2021, securities with a carrying value of $491.2 million and $2.2 billion, respectively, were pledged to secure public deposits and for other purposes required by law. As of March 31, 2022 and December 31, 2021, deposits with associated pledged collateral included Eastern Wealth Management cash accounts and municipal accounts. At March 31, 2022 and December 31, 2021, the carrying value of securities pledged as collateral with respect to municipal accounts acquired from Century Bancorp, Inc. (“Century”) was approximately $461.9 million and $2.1 billion, respectively. During the first quarter of 2022, the Company eliminated certain pledging arrangements acquired from Century which resulted in the decrease in securities pledged at March 31, 2022 compared to December 31, 2021.