equal to the greatest of the prime rate, the federal funds effective rate plus 0.50% or LIBOR plus 1.00%) (the “Base Rate”), plus a margin determined by the Operating Partnership’s corporate credit rating of between 0.00% and 0.40%. The Credit Facility includes a facility fee determined by the Operating Partnership’s corporate credit rating of between 0.10% and 0.30% on the aggregate revolving commitments under the Credit Facility. The Credit Facility contains a money market competitive bid option program that allows the Operating Partnership to hold auctions to achieve lower pricing for short-term borrowings.
The Supplemental Facility’s initial borrowing capacity of $3.5 billion may be increased to $4.5 billion during its term and provides for borrowings denominated in U.S. dollars, Euro, Yen, Sterling, Canadian dollars and Australian dollars. The initial maturity date of the Supplemental Facility is June 30, 2022 and can be extended for an additional year to June 30, 2023 at our sole option, subject to our continued compliance with the terms thereof. The base interest rate on the Supplemental Facility is LIBOR plus 77.5 basis points with a facility fee of 10 basis points.
In October 2021, we amended and extended the Supplemental Facility. The newly refinanced facility will initially mature on January 31, 2026 and can be extended for an additional year to January 31, 2027 at the Company’s sole option, subject to satisfying certain customary conditions precedent. The facility provides for borrowings denominated in U.S. Dollars, Euro, Yen, Sterling, Canadian Dollars, and Australian Dollars.
Borrowings under the Supplemental Facility bear interest, at the Company’s election, at either (i) (x) for Term Benchmark Loans, the Adjusted Term SOFR Rate, the applicable Local Rate, the Adjusted EURIBOR Rate, or the Adjusted TIBOR Rate, (y) for RFR Loans, if denominated in Sterling, SONIA plus a benchmark adjustment and if denominated in Dollars, Daily Simple SOFR plus a benchmark adjustment, or (z) for Daily SOFR Loans, the Adjusted Floating Overnight Daily SOFR Rate, in each case of clauses (x) through (z) above, plus a margin determined by the Company’s corporate credit rating of between 0.650% and 1.400% or (ii) for loans denominated in U.S. Dollars only, the base rate (which rate is equal to the greatest of the prime rate, the federal funds effective rate plus 0.500% or Adjusted Term SOFR Rate for one month plus 1.000%) (the “Base Rate”), plus a margin determined by the Company’s corporate credit rating of between 0.000% and 0.400%. The Supplemental Facility includes a facility fee determined by the Company’s corporate credit rating of between 0.100% and 0.300% on the aggregate revolving commitments under the Supplemental Facility. Based upon the Company’s current credit ratings, the interest rate on the new revolver is SOFR plus 72.5 basis points, plus a spread adjustment to account for the transition from LIBOR to SOFR.
The Operating Partnership also has available a Commercial Paper program of $2.0 billion, or the non-U.S. dollar equivalent thereof. The Operating Partnership may issue unsecured commercial paper notes, denominated in U.S. dollars, Euro and other currencies. Notes issued in non-U.S. currencies may be issued by one or more subsidiaries of the Operating Partnership and are guaranteed by the Operating Partnership. Notes are sold under customary terms in the U.S. and Euro commercial paper note markets and rank (either by themselves or as a result of the guarantee described above) pari passu with the Operating Partnership’s other unsecured senior indebtedness. The Commercial Paper program is supported by the Credit Facilities and if necessary or appropriate, we may make one or more draws under either of the Credit Facilities to pay amounts outstanding from time to time on the Commercial Paper program. On September 30, 2021, we had $500.0 million outstanding under the Commercial Paper program, fully comprised of U.S. dollar-denominated notes with a weighted average interest rate of 0.20%. These borrowings have a weighted average maturity date of November 1, 2021 and reduce amounts otherwise available under the Credit Facilities.
On January 21, 2021, the Operating Partnership completed the issuance of the following senior unsecured notes: $800 million with a fixed interest rate of 1.75%, and $700 million with a fixed interest rate of 2.20%, with maturity dates of February 2028 and 2031, respectively.
On January 27, 2021, the Operating Partnership completed the optional redemption of its $550 million 2.50% notes due on July 15, 2021. We recorded a $3.0 million loss on extinguishment of debt as a result of the optional redemption. Further, on February 2, 2021, the Operating Partnership repaid $750 million under the Term Facility.
On March 19, 2021, the Operating Partnership completed the issuance of €750 million ($893.0 million U.S. dollar equivalent as of the issuance date) of senior unsecured notes at a fixed rate of 1.125% with a maturity date of March 19, 2033. Further, on March 23, 2021, the Operating Partnership repaid the remaining $1.25 billion under the Term Facility reducing it to zero.
On August 18, 2021, the Operating Partnership completed the issuance of the following senior unsecured notes: $550 million with a fixed interest rate of 1.375%, and $700 million with a fixed interest rate of 2.250%, with maturity dates of January 15 2027 and 2032, respectively.
In the third quarter, the Operating Partnership completed the optional redemption of all of its outstanding $550 million 2.350% notes due on January 30, 2022, $600 million 2.625% notes due on June 15, 2022, and $500 million 2.750% notes due on February 1, 2023. We recorded a $28.6 million loss on extinguishment of debt as a result of the optional redemptions.
Mortgage Debt
Total mortgage indebtedness was $6.6 billion and $7.0 billion at September 30, 2021 and December 31, 2020, respectively.