premium, which varied from 1.05% up to 5.25% depending on the period when the embedded call option was exercised by us. As of December 31, 2019, we had $17,974 of the 2021 Bonds outstanding carried at fair value of $18,611 of which $18,242 was non-current and $369 was current.
Through October 2019 we made redemption payments for Notes of $4,480 of which $1,541 related to payments for Notes that had been redeemed in 2018 and $2,939 related to redemption on maturity of all remaining outstanding convertible Notes issued in 2017.
On October 18, 2019, we closed an agreement with Edison Partners IX, LP, or Edison Partners, for a growth equity investment of $15,500, of which $6,975 was new equity and warrants. Subsequently, we secured an additional $500 equity investment from a third party in the beginning of 2020.
Through March 2020, we repurchased on the open market 2021 Bonds with a nominal amount (including accrued interest) of EUR 4,364 (USD 4,975 for the year ended December 31, 2020 and USD 4,812 for the three months ended March 31, 2020), in exchange for a cash payment of EUR 3,123 (USD 3,567 for the year ended December 31, 2020 and USD 3,444 for the three months ended March 31, 2020). The repurchased 2021 Bonds were initially held in treasury and subsequently cancelled.
During the second quarter of 2020, we received a $180 loan from an unsecured bank loan in the U.S. in connection with the COVID-19 paycheck protection program, or the PPP loan, as part of the CARES Act. The loan is repayable in monthly instalments from April 2021 to May 2022, bears interest at 1% per annum and could be forgiven to the extent proceeds of the loan are used for eligible expenditures, such as payroll and other expenses described in the CARES Act. As the Group reasonably believes that it will meet the terms for forgiveness, the loan is accounted for as a grant related to income and initially recognized as a deferred income liability. Subsequent to initial recognition, the Company reduced the liability, with the offset presented as a reduction of the related expense (i.e., payroll related costs) during the year ended December 31, 2020.
On December 7, 2020, in lieu of the exercise of warrants issued in 2019, we closed a share subscription agreement with Charles Gillespie, Kevin McCrystle, Mark Blandford, Edison Partners, and other parties thereto for a growth equity investment of $3,000 in new equity.
In December 2020, we and an investor entered into a $6,000 two-year term loan carrying interest at 8%, or the term loan. The term loan is secured by shares in our subsidiaries.
On December 29, 2020, we fully redeemed the remaining 2021 Bonds at 103.15% plus accrued interest which totaled $14,050.
We estimate based on cash on hand, cash generated from operations and proceeds from additional financings, that we will have adequate liquidity to fund operations for at least twelve months from the issuance date of our consolidated financial statements.
Working Capital
Our working capital is mainly comprised of cash and cash equivalents, trade and other receivables and trade and other payables. Our working capital increased $3,051, or 44% from December 31, 2019 to December 31, 2020. As of December 31, 2019, our working capital equaled $7,008 comprising of cash and cash equivalents of $6,992 and trade and other receivables of $2,367 less trade and other payables of $1,181, borrowings and accrued interest of $369, lease liability of $393 and income tax payable of $408. As of December 31, 2020, our working capital equaled $10,059 comprising of cash and cash equivalents of $8,225 and trade and other receivables of $5,506 less trade and other payables of $2,428, borrowings and accrued interest of $23, lease liability of $413 and income tax payable of $808. Our working capital increased $4,514, or 45%, from December 31, 2020 to March 31, 2021. As of March 31, 2021, our working capital equaled $14,573 comprising of cash and cash equivalents of $14,035 and trade and other receivables of $6,390 less trade and other payables of $4,098 borrowings and accrued interest of $2, lease liability of $396 and income tax payable of $1,356. Our trade and other receivables are amounts due from customers for services performed in the ordinary course of business. Such balances are typically classified as current. Our trade and other payables are obligations to pay for services that have been acquired in the ordinary course of business from suppliers. We believe that our current working capital is sufficient to support our operations for the next twelve months.
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