A summary of long-term debt at December 31, including related interest rates at December 31, 2023, follows (dollars in millions):


	2023			2022
Senior secured asset-based revolving credit facility (effective interest rate of 6.7%)	$	1,880		$	2,900
Senior secured revolving credit facility		—			—
Senior secured term loan facilities (effective interest rate of 6.8%)		1,313			1,880
Other senior secured debt (effective interest rate of 4.1%)		967			953
Senior secured debt		4,160			5,733
Senior unsecured notes (effective interest rate of 5.0%)		35,766			32,652
Debt issuance costs and discounts		(333	)		(301	)
Total debt (average life of 9.4 years, rates averaging 5.1%)		39,593			38,084
Less amounts due within one year		2,424			370
	$	37,169		$	37,714

During 2023, the availability under our senior secured revolving credit facility was increased by $1.500 billion to total $3.500 billion, the senior secured term loan B facility was fully retired and certain administrative updates were made to our credit agreements. We also issued $3.250 billion aggregate principal amount of senior notes comprised of (i) $1.000 billion aggregate principal amount of 5.200% senior notes due 2028, (ii) $1.250 billion aggregate principal amount of 5.500% senior notes due 2033 and (iii) $1.000 billion aggregate principal amount of 5.900% senior notes due 2053. We used the net proceeds to repay borrowings under our asset-based revolving credit facility.

We have entered into the following senior secured credit facilities: (i) a $4.500 billion asset-based revolving credit facility maturing on June 30, 2026 with a borrowing base of 85% of eligible accounts receivable, subject to customary reserves and eligibility criteria ($1.880 billion outstanding at December 31, 2023) (the “ABL credit facility”); (ii) a $3.500 billion senior secured revolving credit facility maturing on June 30, 2026 (none outstanding at December 31, 2023 without giving effect to certain outstanding letters of credit); and (iii) a $1.313 billion senior secured term loan facility maturing on June 30, 2026. We refer to the facilities described under (ii) and (iii) above, collectively, as the “cash flow credit facility” and, together with the ABL credit facility, the “senior secured credit facilities.” Finance leases and other secured debt totaled $967 million at December 31, 2023.

Borrowings under the senior secured credit facilities bear interest at a rate equal to, at our option, either (a) a base rate determined by reference to the higher of (1) the federal funds rate plus 0.50% or (2) the prime rate of Bank of America or (b) a reference rate (the Secured Overnight Financing Rate (SOFR)) for the relevant interest period, plus, in each case, an applicable margin. The applicable margin for borrowings under the senior secured credit facilities may be reduced subject to attaining certain leverage ratios.

The senior secured credit facilities contain a number of covenants that restrict, subject to certain exceptions, our (and some or all of our subsidiaries’) ability to incur additional indebtedness, repay subordinated indebtedness, create liens on assets, sell assets, make investments, loans or advances, engage in certain transactions with affiliates, pay dividends and distributions, and enter into sale and leaseback transactions. In addition, we are required to satisfy and maintain a maximum total leverage ratio covenant under the cash flow credit facility and, in certain situations under the ABL credit facility, a minimum interest coverage ratio covenant.

Senior unsecured notes consist of (i) $35.041 billion aggregate principal amount of senior notes with maturities ranging from 2024 to 2053; (ii) an aggregate principal amount of $125 million medium-term notes maturing 2025; and (iii) an aggregate principal amount of $600 million debentures with maturities ranging from 2024 to 2095.

The senior secured credit facilities are fully and unconditionally guaranteed by substantially all existing and future, direct and indirect, 100% owned material domestic subsidiaries that are “Unrestricted Subsidiaries” under our Indenture (the “1993 Indenture”) dated December 16, 1993 (except for certain special purpose subsidiaries that only guarantee and pledge their assets under our ABL credit facility).

All obligations under the ABL credit facility, and the guarantees of those obligations, are secured, subject to permitted liens and other exceptions, by a first-priority lien on substantially all of the receivables of the borrowers and each guarantor under such ABL credit facility (the “Receivables Collateral”).

All obligations under the cash flow credit facility and the guarantees of such obligations are secured, subject to permitted liens and other exceptions, by:

Maturities of long-term debt in years 2025 through 2028 are $4.672 billion, $5.350 billion, $2.408 billion and $2.545 billion, respectively.