Days” (as defined in the 2018 Indenture), whether or not consecutive, during any 30 consecutive VWAP Trading Day period commencing on or after the date we first issued the 2018 Notes.
On November 6, 2020, we entered into a privately negotiated agreement with an investor who is a holder of our 2018 Notes to exchange approximately $28.0 million aggregate principal amount of 2018 Notes for approximately $28.0 million aggregate principal amount of newly issued 5.00% Convertible Senior Notes due 2048 (the 2020 Notes). The issuance of the 2020 Notes closed on November 13, 2020. The 2020 Notes are governed pursuant to the Base Indenture between us and Wilmington dated as of October 17, 2018 as supplemented by the second supplemental indenture thereto dated as of November 13, 2020 (the 2020 Notes Supplemental Indenture and together with the Base Indenture, the 2020 Indenture).
We had the right, exercisable at our option, to cause all 2020 Notes then outstanding to be converted automatically if the “Daily VWAP” (as defined in the 2020 Indenture) per share of our common stock equals or exceeds 123.08% of the conversion price on each of at least 20 “VWAP Trading Days” (as defined in the 2020 Indenture), whether or not consecutive, during any 30 consecutive VWAP Trading Day period commencing on or after the date we first issued the 2020 Notes (2020 Notes Mandatory Conversion Option).
The initial conversion rate for the 2020 Notes was 307.6923 shares of our common stock per $1,000 principal amount of the 2020 Notes, which is equivalent to an initial conversion price of approximately $3.25 per share, representing an approximately 153.9% premium to the sale price of $1.28 per share of our common stock on November 5, 2020, as reported on the Nasdaq Global Market. The conversion rate was subject to adjustment from time to time upon the occurrence of certain events, including, but not limited to, the issuance of stock dividends and payment of cash dividends, but was not subject to adjustment for any accrued and unpaid interest.
Prior to November 1, 2023, we did not have the option to redeem the 2020 Notes. On or after November 1, 2023, we had the option to redeem the 2020 Notes, in whole or in part, at a cash redemption price equal to the principal amount of the 2020 Notes to be redeemed, plus accrued and unpaid interest, if any.
Unless we had previously called all outstanding 2020 Notes for redemption, the 2020 Notes were subject to repurchase by us at the holders’ option on each of November 1, 2023, November 1, 2028, November 1, 2033, November 1, 2038 and November 1, 2043 (or, if any such date is not a business day, on the next business day) at a cash repurchase price equal to the principal amount of the 2020 Notes to be repurchased, plus accrued and unpaid interest, if any.
The 2020 Notes were our senior unsecured obligations and were senior in right of payment to our future indebtedness that is expressly subordinated in right of payment to the 2020 Notes, and equal in right of payment with our existing and future indebtedness that is not so subordinated, and effectively subordinated to our existing and future indebtedness, to the extent of the value of the collateral securing such indebtedness. The 2020 Notes were structurally subordinated to all existing and future indebtedness and other liabilities, including trade payables, and (to the extent we are not a holder thereof) preferred equity, if any, of our subsidiaries.
On July 1, 2021, we exercised our 2020 Notes Mandatory Conversion Option for the aggregate principal amount of $28.0 million of the 2020 Notes. On July 16, 2021, the aggregate principal of $28.0 million of 2020 Notes was converted into 8,615,384 shares of common stock. Upon conversion of the 2020 Notes, holders received a cash payment equal to the accrued and unpaid interest on the converted 2020 Notes.
As a result, as of September 30, 2021, all 2020 Notes have converted into shares of common stock.
As of September 30, 2021, there was $0.3 million aggregate principal amount outstanding of 2018 Notes. As of December 31, 2020, there was $0.3 million and $28.0 million aggregate principal amount outstanding of 2018 Notes and 2020 Notes, respectively, for a total of $28.3 million aggregate principal amount outstanding.