projected cash flows from operations could cause us to increase our reliance on available funds from the Credit Facilities and Commercial Paper program, further curtail planned capital expenditures, or seek other additional sources of financing.
Financing and Debt
Unsecured Debt
At March 31, 2023, our unsecured debt consisted of $20.4 billion of senior unsecured notes of the Operating Partnership and $125.0 million outstanding under the Credit Facility and $815.8 million (U.S. dollar equivalent) of Euro-denominated borrowings outstanding under the Supplemental Facility.
At March 31, 2023, we had an aggregate available borrowing capacity of $7.6 billion under the Credit Facilities. The maximum aggregate outstanding balance under the Credit Facilities during the three months ended March 31, 2023 was $940.8 million and the weighted average outstanding balance was $940.8 million. Letters of credit of $9.9 million were outstanding under the Credit Facilities as of March 31, 2023.
On March 14, 2023, we amended, restated, extended, and increased our existing $4.0 billion unsecured revolving credit facility. The Credit Facility has an initial borrowing capacity of $5.0 billion which may be increased in the form of additional commitments in the aggregate not to exceed $1.0 billion, for a total aggregate size of $6.0 billion, subject to obtaining additional lender commitments and satisfying certain customary conditions precedent. Borrowings may be denominated in U.S. dollars, Euro, Yen, Pounds Sterling, Canadian dollars and Australian dollars. Borrowings in currencies other than the U.S. dollar are limited to 97% of the maximum revolving credit amount, as defined. The initial maturity date of the Credit Facility was extended to June 30, 2027. The Credit Facility can be extended for two additional six-month periods to June 30, 2028, at our sole option, subject to satisfying certain customary conditions precedent.
Borrowings under the Credit Facility bear interest, at our 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 our 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 our corporate credit rating of between 0.000% and 0.400%. The Credit Facility includes a facility fee determined by our corporate credit rating of between 0.100% and 0.300% on the aggregate revolving commitments under the Credit Facility. Based upon our current credit ratings, the interest rate on the Credit Facility is SOFR plus 72.5 basis points, plus a spread adjustment to account for the transition from LIBOR to SOFR.
The Supplemental Facility’s 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, Pounds, Sterling, Canadian dollars and Australian dollars. Borrowings in currencies other than the U.S. dollar are limited to 100% of the maximum revolving credit amount, as defined. The initial maturity date of the Supplemental Facility is January 31, 2026 and can be extended for an additional year to January 31, 2027 at our sole option, subject to satisfying certain customary conditions precedent.
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 our 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 our corporate credit rating of between 0.000% and 0.400%. The Supplemental Facility includes a facility fee determined by our corporate credit rating of between 0.100% and 0.300% on the aggregate revolving commitments under the Supplemental Facility. Based upon our current credit ratings, the interest rate on the Supplemental Facility 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