The following table presents information about the Company’s financial assets that were carried at fair value on a recurring basis on the consolidated balance sheet as of December 31, 2021 and December 31, 2020 and indicates the fair value hierarchy of the valuation inputs utilized to determine such fair value.

See Note 4 for further details on the short-term investments held. The other asset above relates to advance payments made to a supplier over the period June 2016 to January 2020 that were recorded at fair value using DCF analysis as of December 31, 2020 based on the terms of the original agreement. An amendment to this agreement was signed in December 2021 and these amounts are now recorded as an intangible asset. See Note 6 for further details of this intangible asset.

The carrying amounts reported in the consolidated balance sheets for prepaid expenses and other current assets, accounts payable, accrued expenses and other current liabilities approximate their fair value based on the short-term maturity of these instruments.

The following table presents information about the Company’s debt, Exchangeable Notes, Derivative liability and RLNs and indicates the fair value hierarchy of the valuation inputs utilized to determine the approximate fair value. The Company’s long-term debt and Exchangeable Notes were carried at amortized cost on the consolidated balance sheet as of December 31, 2021 and December 31, 2020, and the RLNs were carried at amortized cost on the consolidated balance sheet as of December 31, 2020.

The book value of the current portion of long-term debt approximates its fair value due to the short-term nature of the balance. The fair value of long-term debt, less current portion was determined based on a DCF analysis using quoted market interest rates, without consideration of transaction costs, which represents a Level 2 basis of fair value measurement. The counterparty to the long-term debt is a major international financial institution.

The fair value of long-term Exchangeable Notes was determined using DCF analysis using the fixed interest rate outlined in the indenture governing the Exchangeable Notes (Exchangeable Note Indenture), without consideration of transaction costs, which represents a Level 2 basis of fair value measurement.

The Level 3 liabilities held as of December 31, 2021 consist of the embedded exchange option and change of control premium contained in the Exchangeable Notes (see Note 10 – Debt) and a separate financial instrument, that was issued as part of the Units, the RLNs (see Note 11 – Royalty-Linked Notes). The exchange option and change of control premium met the criteria requiring these to be bifurcated and accounted for separately from the host debt in accordance with ASC 815-15, Derivatives and Hedging; Embedded Derivatives. The exchange option and change of control premium are presented as a Derivative liability upon issuance of the Exchangeable Notes under the Private Placement and Rights Offering and are subsequently remeasured to fair value at the end of each reporting period. At any time on or after January 21, 2021, subject to specified limitations, the Exchangeable Notes are exchangeable for the Company’s ordinary shares, cash or a combination of ordinary shares and cash, at an exchange rate of 1,286.1845 shares per $1,000 principal and interest on the Exchangeable Note (equivalent to an exchange price of approximately $0.7775 per ordinary share) as of November 2, 2020, what was adjusted from the initial exchange rate of 1,000 shares per $1,000 of principal and interest on the Exchangeable Notes (equivalent to an initial exchange price of approximately $1.00 per ordinary share) and is subject to further adjustment pursuant to the terms of the Exchangeable Note Indenture. Beginning on January 21, 2021 to December 31, 2021, certain noteholders of $39,201 aggregate principal amount of Exchangeable Notes have exchanged their notes for an aggregate of 53,888,331 of the Company’s ordinary shares, which included accrued and unpaid interest relating to such notes. The aggregate principal amount of Exchangeable Notes outstanding as of December 31, 2021 was $12,607. The fair value of the exchange option at December 31, 2021 is $4,565.

In the event of a fundamental change that is not a liquidation event (Fundamental Change), under the Exchangeable Note Indenture, the Company will be required to pay each holder of an Exchangeable Note the greater of three times the outstanding principal amount of such Exchangeable Note and the consideration that would be received by the holder of such Exchangeable Note, in connection with such Fundamental Change, if the holder had exchanged its note for ordinary shares immediately prior to the consummation of such Fundamental Change, plus any accrued and unpaid interest. The Derivative liability, representing the change of control feature, was recorded at a fair value of $1,493 at December 31, 2021.

The fair value of each component of the Derivative liability was determined using the binomial option pricing model, and in the case of the change of control component, in combination with a DCF analysis, without consideration of transaction costs, which represents a Level 3 basis of fair value measurement. The key inputs to valuing the Derivative liability as of December 31, 2021 include the terms of the Exchangeable Notes Indenture, the Company’s share price and market capitalization, the expected annual volatility of the Company’s ordinary shares, management’s assumption regarding the probability of a Fundamental Change pursuant to the terms of the Exchangeable Notes Indenture, and the risk-free interest rate. Fair value measurements are highly sensitive to changes in these inputs and significant changes in these inputs could result in a significantly higher or lower fair value.

The following table presents the changes in fair value of the Company's Derivative liability for the years ended December 31, 2021 and 2020:

The following summary table shows the assumptions used in the binomial option pricing model to estimate the fair value of the exchange option:

The additional significant assumption used in the DCF model, to estimate the fair value of the change of control feature at December 31, 2021, was management’s assumption regarding the probability of a fundamental change pursuant to the terms of the Exchangeable Notes Indenture.

 The RLN liability is carried at fair value on the consolidated balance sheet as of December 31, 2021 (amortized cost as of December 31, 2020) (see Note 11 – Royalty-Linked Notes). The total fair value of $17,968 was determined using DCF analysis, without consideration of transaction costs, which represents a Level 3 basis of fair value measurement. The key inputs to valuing the RLNs were the terms of the indenture governing the RLNs (RLN Indenture), the expected cash flows to be received by holders of the RLNs based on management’s revenue forecasts of U.S. sulopenem sales and a risk-adjusted discount rate to derive the net present value of expected cash flows. The RLNs will be subject to a maximum return amount, including all principal and payments and certain default interest in respect of uncurable defaults, of $160.00 (or 4,000 times the principal amount of such note). The discount rate applied to the model was 20% and 21% for the years ended December 31, 2021 and 2020, respectively. Fair value measurements are highly sensitive to changes in these inputs and significant changes in these inputs could result in a significantly higher or lower fair value.

There have been no transfers of assets or liabilities between the fair value measurement levels.