| Cash Equivalents and Investments |
Cash Equivalents and Investments Marketable debt securities held by the Company are classified as available-for-sale pursuant to ASC 320, Investments – Debt and Equity Securities, and carried at fair value in the balance sheets on a settlement date basis. The following tables summarize the gross unrealized gains and losses of the Company’s marketable securities as of December 31, 2020 and December 31, 2019:
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | December 31, 2020 | | | | | Gross Unrealized | | | | | Amortized Cost | | Gains | | Losses | | Credit Losses | | Estimated Fair Value | | Money market funds | | $ | 3,698 | | | $ | — | | | $ | — | | | $ | — | | | $ | 3,698 | | | Commercial paper | | 8,993 | | | 1 | | | — | | | — | | | 8,994 | | | Corporate notes | | 35,917 | | | — | | | — | | | (6) | | | 35,911 | | | U.S. government securities | | 12,828 | | | 14 | | | — | | | — | | | 12,842 | | | U.S. government agency bonds | | 5,000 | | | 1 | | | — | | | — | | | 5,001 | | | U.S. asset-backed securities | | 3,534 | | | 4 | | | — | | | — | | | 3,538 | | | | $ | 69,970 | | | $ | 20 | | | $ | — | | | $ | (6) | | | $ | 69,984 | | | Classified as: | | | | | | | | | | | | Cash equivalents | | | | | | | | | | $ | 3,698 | | | Short-term investments | | | | | | | | | | 42,187 | | | Long-term investments | | | | | | | | | | 24,099 | | | | | | | | | | $ | 69,984 | |
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | December 31, 2019 | | | | | Gross Unrealized | | | | (In thousands) | | Amortized Cost | | Gains | | Losses | | Estimated Fair Value | | Money market funds | | $ | 5,381 | | | $ | — | | | $ | — | | | $ | 5,381 | | | | | | | | | | | | Commercial paper | | 11,892 | | | — | | | — | | | 11,892 | | | Corporate notes | | 18,369 | | | 11 | | | — | | | 18,380 | | | U.S. government securities | | 11,291 | | | 4 | | | — | | | 11,295 | | | U.S. asset-backed securities | | 10,503 | | | 6 | | | — | | | 10,509 | | | | $ | 57,436 | | | $ | 21 | | | $ | — | | | $ | 57,457 | | | Classified as: | | | | | | | | | | Cash equivalents | | | | | | | | $ | 5,381 | | | Short-term investments | | | | | | | | 42,829 | | | Long-term investments | | | | | | | | 9,247 | | | | | | | | $ | 57,457 | |
As of December 31, 2020, the analysis under ASU 326 and the current macroeconomic impact of the COVID-19 pandemic did not result in material allowances for credit losses. There have been no impairments of the Company’s assets measured and carried at fair value as of December 31, 2020.
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