Note 6 — Investment Securities, Equity Securities with Readily Determinable Fair Values and Other Investments

We classify debt securities into one of three categories: held-to-maturity, available-for-sale, or trading. Such debt securities are reassessed for appropriate classification at each reporting date. Securities classified as “held-to-maturity” are carried at amortized cost for financial statement reporting, while securities classified as “available-for-sale” and “trading” are carried at their fair value. Unrealized holding gains and losses are included in net income for those securities classified as “trading,” while unrealized holding gains and losses related to those securities classified as “available-for-sale” are excluded from net income and reported net of tax as other comprehensive income (loss) and accumulated other comprehensive income (loss) until realized, or in the case of losses, when deemed other than temporary. Available-for-sale and held-to-maturity debt securities in an unrealized loss position are evaluated for the underlying cause of the loss. In the event that the deterioration in value is attributable to credit related reasons, then the amount of credit-related impairment will be recorded as a charge to our ACL with subsequent changes in the amount of impairment, up or down, also recorded through our ACL. We have evaluated the debt securities classified as available-for-sale and held-to-maturity at March 31, 2022 and have determined that no debt securities in an unrealized loss position are arising from credit related reasons and have therefore not recorded any allowances for debt securities in our ACL for the period. Unrealized gains and losses related to equity securities with readily determinable fair values are included in net income.

The amortized cost and estimated fair value by type of investment security at March 31, 2022 are as follows:

(1)	Included in the carrying value of residential mortgage-backed securities are $734,878 of mortgage-backed securities issued by Ginnie Mae and $3,315,475 of mortgage-backed securities issued by Fannie Mae and Freddie Mac.

The amortized cost and estimated fair value by type of investment security at December 31, 2021 are as follows:


	Held to Maturity
			Gross		Gross
	Amortized		unrealized		unrealized		Estimated		Carrying
	cost		gains		losses		fair value		value

	(Dollars in Thousands)
Other securities	$	3,400	$	—	$	—	$	3,400	$	3,400
Total investment securities	$	3,400	$	—	$	—	$	3,400	$	3,400


	Available for Sale
			Gross		Gross		Estimated
	Amortized		unrealized		unrealized		fair		Carrying
	cost		gains		losses		value		value⁽¹⁾

	(Dollars in Thousands)
Residential mortgage-backed securities	$	4,213,441	$	14,159	$	(58,237)	$	4,169,363	$	4,169,363
Obligations of states and political subdivisions		41,519		3,038		—		44,557		44,557
Total investment securities	$	4,254,960	$	17,197	$	(58,237)	$	4,213,920	$	4,213,920

(1)	Included in the carrying value of residential mortgage-backed securities are $824,474 of mortgage-backed securities issued by Ginnie Mae and $3,344,899 of mortgage-backed securities issued by Fannie Mae and Freddie.

The amortized cost and estimated fair value of investment securities at March 31, 2022, by contractual maturity, are shown below. Expected maturities will differ from contractual maturities because borrowers may have the right to prepay obligations with or without prepayment penalties.


	Held to Maturity				Available for Sale
	Amortized		Estimated		Amortized		Estimated
	Cost		fair value		Cost		fair value

	(Dollars in Thousands)
Due in one year or less	$	2,325	$	2,325	$	—	$	—
Due after one year through five years		1,075		1,075		49,099		49,099
Due after five years through ten years		—		—		—		—
Due after ten years		—		—		41,454		42,545
Residential mortgage-backed securities		—		—		4,313,749		4,050,353
Total investment securities	$	3,400	$	3,400	$	4,404,302	$	4,141,997

Residential mortgage-backed securities are securities primarily issued by the Federal Home Loan Mortgage Corporation (“Freddie Mac”), Federal National Mortgage Association (“Fannie Mae”), or the Government National Mortgage Association (“Ginnie Mae”). Investments in residential mortgage-backed securities issued by Ginnie Mae are fully guaranteed by the U.S. Government. Investments in residential mortgage-backed securities issued by Freddie Mac and Fannie Mae are not fully guaranteed by the U.S. Government, however, we believe that the quality of the bonds is similar to other AAA rated bonds with limited credit risk, particularly given the placement of Fannie Mae and Freddie Mac into conservatorship by the federal government in early September 2008 and because securities issued by others that are collateralized by residential mortgage-backed securities issued by Fannie Mae or Freddie Mac are rated consistently as AAA rated securities.

The amortized cost and fair value of available-for-sale debt investment securities pledged to qualify for fiduciary powers, to secure public monies as required by law, repurchase agreements and short-term fixed borrowings was $1,517,343,000 and $1,405,511,000, respectively, at March 31, 2022.

Proceeds from the sale and calls of debt securities available-for-sale were $0 for the three months ended March 31, 2022, which included $0 of mortgage-backed securities. Gross gains of $0 and gross losses of $0 were realized on the sales and calls for the three months ended March 31, 2022. Proceeds from the sale and call of debt securities available-for-sale were $2,510,000 for the three months ended March 31, 2021, which included $0 of mortgage-backed securities. Gross gains of $0 and gross losses of $4 were realized on the sales and calls for the three months ended March 31, 2021, respectively.

Gross unrealized losses on debt investment securities and the fair value of the related securities, aggregated by investment category and length of time that individual debt securities have been in a continuous unrealized loss position at March 31, 2022, were as follows:


	Less than 12 months				12 months or more				Total
			Unrealized				Unrealized				Unrealized
	Fair Value		Losses		Fair Value		Losses		Fair Value		Losses

	(Dollars in Thousands)
Available for sale:
Residential mortgage-backed securities	$	3,181,601	$	(237,429)	$	515,872	$	(28,100)	$	3,697,473	$	(265,529)
	$	3,181,601	$	(237,429)	$	515,872	$	(28,100)	$	3,697,473	$	(265,529)

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 December 31, 2021 were as follows:


	Less than 12 months				12 months or more				Total
			Unrealized				Unrealized				Unrealized
	Fair Value		Losses		Fair Value		Losses		Fair Value		Losses

	(Dollars in Thousands)
Available for sale:
Residential mortgage-backed securities	$	3,037,188	$	(53,060)	$	423,733	$	(5,177)	$	3,460,921	$	(58,237)
	$	3,037,188	$	(53,060)	$	423,733	$	(5,177)	$	3,460,921	$	(58,237)

The unrealized losses on investments in residential mortgage-backed securities are primarily caused by changes in market interest rates. We have no intent to sell and will more than likely not be required to sell before a market price recovery or maturity of the securities; therefore, it is our conclusion that the investments in residential mortgage-backed securities issued by Freddie Mac, Fannie Mae and Ginnie Mae are not considered other-than-temporarily impaired.

Equity securities with readily determinable fair values consist primarily of Community Reinvestment Act funds. At March 31, 2022 and December 31, 2021, the balance in equity securities with readily determinable fair values recorded at fair value were $5,810,000 and $6,079,000, respectively. The following is a summary of unrealized and realized gains and losses recognized in net income on equity securities during the three months ended March 31, 2022 and the three months ended March 31, 2021:


	Three Months Ended
	March 31, 2022
	(Dollars in Thousands)


Net losses recognized during the period on equity securities	$	(269)
Less: Net gains and (losses) recognized during the period on equity securities sold during the period		—

Unrealized losses recognized during the reporting period on equity securities still held at the reporting date	$	(269)


	Three Months Ended
	March 31, 2021
	(Dollars in Thousands)


Net losses recognized during the period on equity securities	$	(77)
Less: Net gains and (losses) recognized during the period on equity securities sold during the period		—

Unrealized losses recognized during the reporting period on equity securities still held at the reporting date	$	(77)

Other investments include equity and merchant banking investments held by our subsidiary banks and non-banking entities. We hold ownership interests in limited partnerships for the purpose of investing in low-income housing tax credit (“LIHTC”) projects. The partnerships may acquire, construct or rehabilitate housing for low- and moderate-income individuals. We realize a return primarily from federal tax credits and other federal tax deductions associated with the underlying projects. We are a limited partner in the partnerships, and not required to consolidate the entities in our consolidated financial statements. Investments in LIHTC projects totaled $236,397,000 at March 31, 2022 and $179,543,000 at December 31, 2021, and are included in other investments on the consolidated financial statements.

Unfunded commitments to LIHTC projects totaled $55,108,000 at March 31, 2022 and $40,094,000 at December 31, 2021, and are included in other liabilities on the consolidated financial statements.