2. Marketable securities

Investments in debt securities that are not classified as held-to-maturity are carried at fair value and classified as either trading or available-for-sale. Realized and unrealized gains and losses on trading debt securities as well as realized gains and losses on available-for-sale debt securities are included in net loss.

The following tables show the Company’s fair value marketable securities by investment category as of September 30, 2021 and December 31, 2020:

Level 2 applies to assets or liabilities for which there are inputs other than quoted prices that are observable for the assets or liability such as quoted prices for similar assets or liabilities in active markets, quoted prices for identical assets or liabilities in markets with insufficient volume or infrequent transactions (less active markets), or model-derived valuations in which significant inputs are observable or can be derived principally from, or corroborated by observable market data.

We classify our marketable securities as trading securities as of September 30, 2021.