As of September 30, 2019, we had outstanding $924 million of indebtedness under the unsecured credit facility, consisting of $224.1 million of outstanding borrowings under our unsecured revolving credit facility and $700.0 million outstanding under the term loans, exclusive of net debt issuance costs of $5.5 million. In connection with the unsecured credit facility, as of September 30, 2019, we had additional letters of credit outstanding aggregating to $4.1 million.
On April 5, 2017, we entered into forward interest rate swap agreements with an aggregate notional amount of $400 million. The forward swap agreements effectively fix the interest rate on $400 million of term loan borrowings, $200 million of swaps allocated to the term loans, from January 2, 2018 through December 17, 2021 and April 27, 2022, respectively.
On December 20, 2018, we entered into additional forward interest rate swap agreements with an aggregate notional amount of $400 million. The forward swap agreements effectively fix the interest rate on $400 million of term loan borrowings, $200 million of swaps allocated to each term loan, from December 17, 2021 and April 27, 2022 through the current maturity dates of the respective term loans which are December 17, 2023 and April 27, 2024, respectively. Additionally, we entered into forward interest rate swap agreements with an aggregate notional amount of $200 million. The forward swap agreements effectively fix the interest rate on $200 million of additional term loan borrowings, $100 million of swaps allocated to each term loan, from January 2, 2020 through the current maturity dates of the respective term loans which are December 17, 2023 and April 27, 2024, respectively.
4.750% Senior Notes due 2025. On November 8, 2017, the Operating Partnership and QTS Finance Corporation, a subsidiary of the Operating Partnership initially formed solely for the purpose of facilitating the offering of the 5.875% Senior Notes due 2022 (collectively, the “Issuers”), issued $400 million aggregate principal amount of 4.75% Senior Notes due November 15, 2025 (the “Senior Notes”) in a private offering. The Senior Notes have an interest rate of 4.750% per annum and were issued at a price equal to 100% of their face value. The net proceeds from the offering were used to fund the redemption of, and satisfy and discharge the indenture pursuant to which the Issuers issued the 5.875% Senior Notes due 2022 and to repay a portion of the amount outstanding under the Company’s unsecured revolving credit facility.
The Senior Notes are unconditionally guaranteed, jointly and severally, on a senior unsecured basis by all of the Operating Partnership’s existing subsidiaries (other than certain foreign subsidiaries and receivables entities) and future subsidiaries that guarantee any indebtedness of QTS, the Issuers or any other subsidiary guarantor. QTS Realty Trust, Inc. does not guarantee the Senior Notes and will not be required to guarantee the Senior Notes except under certain circumstances. The offering was conducted pursuant to Rule 144A of the Securities Act of 1933, as amended, and the Senior Notes were issued pursuant to an indenture, dated as of November 8, 2017, among QTS, the Issuers, the guarantors named therein, and Deutsche Bank Trust Company Americas, as trustee (the “Indenture”). As of September 30, 2019, the outstanding net debt issuance costs associated with the Senior Notes were $4.6 million.
The Indenture contains affirmative and negative covenants that, among other things, limits or restricts the Operating Partnership’s ability and the ability of certain of its subsidiaries (the “Restricted Subsidiaries”) to: incur additional indebtedness; pay dividends; make certain investments or other restricted payments; enter into transactions with affiliates; enter into agreements limiting the ability of the Operating Partnership’s restricted subsidiaries to pay dividends; engage in sales of assets; and engage in mergers, consolidations or sales of substantially all of their assets.
However, certain of these covenants will be suspended if and for so long as the Senior Notes are rated investment grade by specified debt rating services and there is no default under the Indenture. The Operating Partnership and its Restricted Subsidiaries also are required to maintain total unencumbered assets (as defined in the Indenture) of at least 150% of their unsecured debt on a consolidated basis.
The Senior Notes may be redeemed by the Issuers, in whole or in part, at any time prior to November 15, 2020 at a redemption price equal to (i) 100% of the principal amount, plus (ii) accrued and unpaid interest to the redemption date, and (iii) a make-whole premium. On or after November 15, 2020, the Issuers may redeem the Senior Notes, in whole or in part, at a redemption price equal to (i) 103.563% of the principal amount from November 15, 2020 to November 14, 2021, (ii) 102.375% of the principal amount from November 15, 2021 to November 14, 2022, (iii) 101.188% of the principal amount from November 15, 2022 to November 14, 2023 and (iv) 100.000% of the principal amount of the