Note 4. Financial Instruments

The following table summarizes the amortized cost and fair value of available-for-sale securities at December 31, 2021 and 2020 (in thousands):

No available-for-sale debt securities held as of December 31, 2021 and 2020 had remaining maturities greater than one year. Unrealized gains and losses on available-for-sale securities are included as a component of comprehensive loss. At December 31, 2021, the Company did not have any securities in material unrealized loss positions.

The Company reviews its investments to identify and evaluate investments that have an indication of possible other-than-temporary impairment. Factors considered in determining whether a loss is other-than-temporary include the length of time and extent to which fair value has been less than the cost basis, the financial condition and near-term prospects of the investee, and the Company’s intent and ability to hold the investment for a period of time sufficient to allow for any anticipated recovery in market value. The Company does not generally sell any investments prior to recovery of their amortized cost basis for any investments in an unrealized loss position.