EQR does not have any indebtedness as all debt is incurred by the Operating Partnership. Weighted average interest rates noted below for the years ended December 31, 2020 and 2019 include the effect of any derivative instruments and amortization of premiums/discounts/OCI (other comprehensive income) on debt and derivatives.

The following tables summarize the Company’s mortgage notes payable activity for the years ended December 31, 2020 and 2019, respectively (amounts in thousands):

	Mortgage notes payable, net as of December 31, 2019		Proceeds			Lump sum payoffs			Scheduled principal repayments			Amortization of premiums/ discounts		Amortization of deferred financing costs, net (1)			Mortgage notes payable, net as of December 31, 2020
Fixed Rate Debt:
Secured – Conventional	$	1,574,699	$	495,000	(2)	$	(160,522	)	$	(7,759	)	$	988	$	(1,315	)	$	1,901,091
Floating Rate Debt:
Secured – Conventional		7,050		24,204			—			—			—		240			31,494
Secured – Tax Exempt		359,861		—			—			—			1,246		198			361,305
Floating Rate Debt		366,911		24,204			—			—			1,246		438			392,799
Total	$	1,941,610	$	519,204		$	(160,522	)	$	(7,759	)	$	2,234	$	(877	)	$	2,293,890

	Mortgage notes payable, net as of December 31, 2018		Proceeds			Lump sum payoffs			Scheduled principal repayments			Amortization of premiums/ discounts			Amortization of deferred financing costs, net (1)			Mortgage notes payable, net as of December 31, 2019
Fixed Rate Debt:
Secured – Conventional	$	1,885,407	$	288,120	(2)	$	(584,536	)	$	(6,308	)	$	(7,999	)	$	15		$	1,574,699
Floating Rate Debt:
Secured – Conventional		6,357		7,651	(3)		(5,920	)		(500	)		—			(538	)		7,050
Secured – Tax Exempt		493,706		—			(152,565	)		—			16,617			2,103			359,861
Floating Rate Debt		500,063		7,651			(158,485	)		(500	)		16,617			1,565			366,911
Total	$	2,385,470	$	295,771		$	(743,021	)	$	(6,808	)	$	8,618		$	1,580		$	1,941,610

The following table summarizes the Company’s debt extinguishment costs on mortgages recorded as additional interest expense during the years ended December 31, 2020 and 2019, respectively (amounts in thousands):

The following table summarizes certain interest rate and maturity date information as of and for the years ended December 31, 2020 and 2019, respectively:

As of both December 31, 2020 and 2019, the Company had $281.7 million of secured debt (primarily tax-exempt bonds) subject to third-party credit enhancement.

The historical cost, net of accumulated depreciation, of encumbered properties was $2.9 billion and $2.7 billion at December 31, 2020 and 2019, respectively.

The following tables summarize the Company’s notes activity for the years ended December 31, 2020 and 2019, respectively (amounts in thousands):

Notes, net as of

December 31, 2019

Proceeds

Lump sum

payoffs

Realized/unrealized

(gain) loss on

derivative

instruments

Amortization

of premiums/

discounts

Amortization

of deferred

financing

costs, net (1)

Notes, net as of

December 31, 2020

Fixed Rate Debt:

Unsecured – Public

6,077,513

—

(750,000

)

—

2,997

5,026

5,335,536

	Notes, net as of December 31, 2018		Proceeds			Lump sum payoffs			Realized/unrealized (gain) loss on derivative instruments		Amortization of premiums/ discounts		Amortization of deferred financing costs, net (1)			Notes, net as of December 31, 2019
Fixed Rate Debt:
Unsecured – Public	$	5,485,884	$	1,194,468	(2)	$	(600,000	)	$	—	$	3,117	$	(5,956	)	$	6,077,513
Floating Rate Debt:
Unsecured – Public		447,402		—			(450,000	)		2,277		45		276			—
Total	$	5,933,286	$	1,194,468		$	(1,050,000	)	$	2,277	$	3,162	$	(5,680	)	$	6,077,513

The following table summarizes the Company’s debt extinguishment costs on notes recorded as additional interest expense during the years ended December 31, 2020 and 2019, respectively (amounts in thousands):

The following table summarizes certain interest rate and maturity date information as of and for the years ended December 31, 2020 and 2019, respectively:

The Company’s unsecured public notes contain certain financial and operating covenants including, among other things, maintenance of certain financial ratios. The Company was in compliance with its unsecured public debt covenants for both the years ended December 31, 2020 and 2019.

EQR and ERPOP currently have an active universal shelf registration statement for the issuance of equity and debt securities that automatically became effective upon filing with the SEC in June 2019 and expires in June 2022.

On November 1, 2019, the Company replaced its existing $2.0 billion facility with a $2.5 billion unsecured revolving credit facility maturing November 1, 2024. The Company has the ability to increase available borrowings by an additional $750.0 million by adding lenders to the facility, obtaining the agreement of existing lenders to increase their commitments or incurring one or more term loans. The interest rate on advances under the facility will generally be LIBOR plus a spread (currently 0.775%), or based on bids received from the lending group, and the Company pays an annual facility fee (currently 0.125%). Both the spread and the facility fee are dependent on the Company’s senior unsecured credit rating. The weighted average interest rates on the revolving credit facility were 1.47% and 3.12% for the years ended December 31, 2020 and 2019, respectively.

On November 4, 2019, the Company increased the maximum aggregate amount outstanding for its commercial paper program from $500.0 million to $1.0 billion. The notes will be sold under customary terms in the United States commercial paper note market subject to market conditions and will rank pari passu with all of the Company’s other unsecured senior indebtedness. The notes bear interest at various floating rates with a weighted average interest rate of 1.72% and 2.42% for the years ended December 31, 2020 and 2019, respectively, and a weighted average maturity of 45 days and 40 days as of December 31, 2020 and 2019, respectively. The weighted average amount outstanding for the years ended December 31, 2020 and 2019 was approximately $276.6 million and $434.4 million, respectively.

The Company limits its utilization of the revolving credit facility in order to maintain liquidity to support its $1.0 billion commercial paper program along with certain other obligations. The following table presents the availability on the Company’s unsecured revolving credit facility as of December 31, 2020 and 2019 (amounts in thousands):

	December 31, 2020			December 31, 2019
Unsecured revolving credit facility commitment	$	2,500,000		$	2,500,000
Commercial paper balance outstanding		(415,000	)		(1,000,000	)
Unsecured revolving credit facility balance outstanding		—			(20,000	)
Other restricted amounts		(100,949	)		(100,929	)
Unsecured revolving credit facility availability	$	1,984,051		$	1,379,071

The following table summarizes the Company’s debt extinguishment costs on the line of credit recorded as additional interest expense during the years ended December 31, 2020 and 2019, respectively (amounts in thousands):

The following table provides a summary of the aggregate payments of principal on all debt for each of the next five years and thereafter as of December 31, 2020 (amounts in thousands):

Year	Total
2021 (1)	$	450,665
2022		296,040
2023		1,329,088
2024		6,100
2025		458,200
Thereafter		5,586,810
Subtotal		8,126,903
Deferred Financing Costs and Unamortized (Discount)		(82,647	)
Total	$	8,044,256