Our investment securities portfolio consists of the following: U.S. government-sponsored enterprise or agency (“Agency”) and non-agency residential mortgage-backed securities (“RMBS”), Agency commercial mortgage-backed securities (“CMBS”), U.S. Treasury securities and other securities. Agency securities include Government National Mortgage Association (“Ginnie Mae”) guaranteed securities, Federal National Mortgage Association (“Fannie Mae”) and Federal Home Loan Mortgage Corporation (“Freddie Mac”) issued securities. The carrying value of our investments in Agency and U.S. Treasury securities represented 96% of our total investment securities portfolio as of both September 30, 2021 and December 31, 2020.

The table below presents the amortized cost, gross unrealized gains and losses, and fair value of securities available for sale as of September 30, 2021 and December 31, 2020. Accrued interest receivable of $227 million and $230 million as of September 30, 2021, and December 31, 2020, respectively, is not included in the table below.


	September 30, 2021
(Dollars in millions)	Amortized Cost		Allowance for Credit Losses		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Investment securities available for sale:
U.S. Treasury securities	$	9,094	$	0	$	15	$	0	$	9,109
RMBS:
Agency	73,924		0		1,325		(617)		74,632
Non-agency	844		(1)		206		0		1,049
Total RMBS	74,768		(1)		1,531		(617)		75,681
Agency CMBS	9,973		0		265		(41)		10,197
Other securities(1)	3,154		0		8		0		3,162
Total investment securities available for sale	$	96,989	$	(1)	$	1,819	$	(658)	$	98,149


	December 31, 2020
(Dollars in millions)	Amortized Cost		Allowance for Credit Losses		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Investment securities available for sale:
U.S. Treasury securities	$	9,302	$	0	$	16	$	0	$	9,318
RMBS:
Agency	73,248		0		2,326		(108)		75,466
Non-agency	1,035		(1)		204		(1)		1,237
Total RMBS	74,283		(1)		2,530		(109)		76,703
Agency CMBS	11,298		0		448		(11)		11,735
Other securities(1)	2,686		0		3		0		2,689
Total investment securities available for sale	$	97,569	$	(1)	$	2,997	$	(120)	$	100,445

(1)Includes $2.3 billion and $1.8 billion of asset-backed securities (“ABS”) as of September 30, 2021, and December 31, 2020, respectively. The remaining amount is primarily comprised of supranational bonds and foreign government bonds.

The table below provides the gross unrealized losses and fair value of our securities available for sale aggregated by major security type and the length of time that individual securities have been in a continuous unrealized loss position as of September 30, 2021 and December 31, 2020. The amounts include securities available for sale without an allowance for credit losses.


	September 30, 2021
	Less than 12 Months				12 Months or Longer				Total
(Dollars in millions)	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
Investment securities available for sale without an allowance for credit losses:

RMBS:
Agency	$	35,415	$	(519)	$	4,068	$	(98)	$	39,483	$	(617)
Non-agency	0		0		1		0		1		0
Total RMBS	35,415		(519)		4,069		(98)		39,484		(617)
Agency CMBS	1,746		(26)		561		(15)		2,307		(41)
Other securities(1)	470		0		0		0		470		0
Total investment securities available for sale in a gross unrealized loss position without an allowance for credit losses(2)	$	37,631	$	(545)	$	4,630	$	(113)	$	42,261	$	(658)


	December 31, 2020
	Less than 12 Months				12 Months or Longer				Total
(Dollars in millions)	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
Investment securities available for sale without an allowance for credit losses:

RMBS:
Agency	$	7,424	$	(57)	$	1,791	$	(51)	$	9,215	$	(108)
Non-agency	12		0		0		0		12		0
Total RMBS	7,436		(57)		1,791		(51)		9,227		(108)
Agency CMBS	1,545		(7)		267		(4)		1,812		(11)
Other securities(1)	114		0		1		0		115		0
Total investment securities available for sale in a gross unrealized loss position without an allowance for credit losses(2)	$	9,095	$	(64)	$	2,059	$	(55)	$	11,154	$	(119)

(2) Consists of approximately 540 and 320 securities in gross unrealized loss positions as of September 30, 2021 and December 31, 2020, respectively.

The table below summarizes, by major security type, the contractual maturities and weighted-average yields of our investment securities as of September 30, 2021. Because borrowers may have the right to call or prepay certain obligations, the expected maturities of our securities are likely to differ from the scheduled contractual maturities presented below. The weighted-average yield below represents the effective yield for the investment securities and is calculated based on the amortized cost of each security.


	September 30, 2021
(Dollars in millions)	Due in 1 Year or Less			Due > 1 Year through 5 Years			Due > 5 Years through 10 Years			Due > 10 Years			Total
Fair value of securities available for sale:
U.S. Treasury securities	$	5,203		$	3,906		$	0		$	0		$	9,109
RMBS(1):
Agency	0			137			1,106			73,389			74,632
Non-agency	0			0			0			1,049			1,049
Total RMBS	0			137			1,106			74,438			75,681
Agency CMBS(1)	570			2,489			4,462			2,676			10,197
Other securities	252			2,585			325			0			3,162
Total securities available for sale	$	6,025		$	9,117		$	5,893		$	77,114		$	98,149
Amortized cost of securities available for sale	$	6,019		$	9,062		$	5,761		$	76,147		$	96,989
Weighted-average yield for securities available for sale	0.31		%	0.72		%	1.66		%	1.71		%	1.53		%

For the three and nine months ended September 30, 2021, total proceeds from sales of our securities were $1.1 billion and $1.7 billion, respectively, with gains of $2 million and $6 million, respectively. For the three and nine months ended September 30, 2020, total proceeds from the sale of our securities were $668 million and $812 million respectively, with gains of $25 million in both periods.

We pledged investment securities totaling $19.6 billion and $16.5 billion as of September 30, 2021 and December 31, 2020, respectively. These securities are primarily pledged to secure FHLB advances and Public Funds deposits, as well as for other purposes as required or permitted by law. We accepted pledges of securities with a fair value of approximately $1 million as of both September 30, 2021 and December 31, 2020, related to our derivative transactions.