Our Series D Term Preferred Stock is not convertible into our common stock or any other security. Our Series D Term Preferred Stock provides for a fixed dividend equal to 6.25% per year, payable monthly (which equates to $3.6 million per year). We are required to redeem all shares of our outstanding Series D Term Preferred Stock on September 30, 2023, for cash at a redemption price equal to $25.00 per share, plus an amount equal to accumulated but unpaid dividends, if any, to, but excluding, the date of redemption. In addition, two other potential mandatory redemption triggers are as follows: (1) upon the occurrence of certain events that would constitute a change in control of us, we would be required to redeem all of our outstanding Series D Term Preferred Stock, and (2) if we fail to maintain asset coverage of at least 200% and are unable to correct such failure within a specific amount of time, we are required to redeem a portion of our outstanding Series D Term Preferred Stock or otherwise cure the asset coverage redemption trigger (and we may also redeem additional securities to cause the asset coverage to be 240%). We may also voluntarily redeem all or a portion of our Series D Term Preferred Stock at our sole option at the redemption price at any time on or after September 30, 2018.
In September 2016, we used a portion of the proceeds from the issuance of our Series D Term Preferred Stock to voluntarily redeem all 1.6 million outstanding shares of our Series A Term Preferred Stock, which had a liquidation preference of $25.00 per share. In connection with this voluntary redemption, we incurred a loss on extinguishment of debt of $0.2 million, which has been recorded in Realized loss on other in our accompanying Consolidated Statements of Operations and which was primarily comprised of unamortized deferred issuance costs at the time of redemption.
Prior to its redemption in September 2016, our Series A Term Preferred Stock provided for a fixed dividend equal to 7.125% per year, payable monthly (which equated to $2.9 million per year). We were required to redeem all of the outstanding Series A Term Preferred Stock on February 28, 2017, for cash at a redemption price equal to $25.00 per share plus an amount equal to accumulated but unpaid dividends, if any, to the date of redemption. Our Series A Term Preferred Stock was not convertible into our common stock or any other security.
Each series of our mandatorily redeemable preferred stock has a preference over our common stock with respect to dividends, whereby no distributions are payable on our common stock unless the stated dividends, including any accrued and unpaid dividends, on the mandatorily redeemable preferred stock have been paid in full. The Series D Term Preferred Stock and Series E Term Preferred Stock are considered liabilities in accordance with GAAP and, as such, affect our asset coverage, exposing us to additional leverage risks. The asset coverage on our senior securities that are stock (our Series D Term Preferred Stock and Series E Term Preferred Stock) as of March 31, 2019 was 309.1%, calculated pursuant to Sections 18 and 61 of the 1940 Act.
Revolving Line of Credit
On August 22, 2018, we, through our wholly-owned subsidiary, Business Investment, entered into Amendment No. 4 to the Fifth Amended and Restated Credit Agreement, originally entered into on April 30, 2013, with KeyBank National Association (“KeyBank”) as administrative agent, lead arranger, managing agent and lender, the Adviser, as servicer, and certain other lenders party thereto. The revolving period was extended to August 22, 2021, and if not renewed or extended by such date, all principal and interest will be due and payable on August 22, 2023 (two years after the revolving period end date). As of March 31, 2019, the Credit Facility provided twoone-year extension options that may be exercised on or before the first and second anniversary of the August 22, 2018 amendment date, subject to approval by all lenders. Additionally, the Credit Facility commitment amount was increased from $165.0 million to $200.0 million and, subject to certain terms and conditions, can be expanded to a total facility amount of $300.0 million through additional commitments from existing or new lenders.
Advances under the Credit Facility generally bear interest at30-day LIBOR plus 2.85% per annum until August 21, 2021, with the margin then increasing to 3.10% for the period from August 22, 2021 to August 21, 2022, and increasing further to 3.35% thereafter. The Credit Facility has an unused commitment fee on the daily unused commitment amount of 0.50% per annum if the average unused commitment amount for the period is less than or equal to 50% of the total commitment amount, 0.75% per annum if the average unused commitment amount for the period is greater than 50% but less than or equal to 65% of the total commitment amount, and 1.00% per annum if the average unused commitment amount for the period is greater than 65% of the total commitment amount. We incurred fees of approximately $1.6 million in connection with this amendment.
Interest is payable monthly during the term of the Credit Facility. Available borrowings are subject to various constraints and applicable advance rates, which are generally based on the size, characteristics, and quality of the collateral pledged by Business Investment. The Credit Facility also requires that any interest and principal payments on pledged loans be remitted directly by the borrower into a lockbox account with KeyBank. KeyBank is also the trustee of the account and generally remits the collected funds to us once a month.
Among other things, the Credit Facility contains covenants that require Business Investment to maintain its status as a separate legal entity, prohibit certain significant corporate transactions (such as mergers, consolidations, liquidations or dissolutions) and restrict certain material changes to our credit and collection policies without the lenders’ consent. The Credit Facility also generally seeks to restrict distributions to stockholders to the sum of (i) our net investment income, (ii) net capital gains, and (iii) amounts deemed by the Company to be considered as having been paid during the prior fiscal year in accordance with Section 855(a) of the Code. Loans eligible to be pledged as collateral are subject to certain limitations, including, among other things, restrictions on geographic concentrations, industry concentrations, loan size, payment frequency and status, average life, portfolio company leverage, and lien property.
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