| Investment Securities |
5. Investment Securities The following represents the Company’s investment securities as of September 30, 2026 and December 31, 2025: | | | | | | | | | | | | | Balance at September 30, 2026 | | | Acquisition
Cost | | | Accretion /
(Amortization) | | | Unrealized
Gain / (Loss) | | | Estimated
Fair Value | Commercial paper | | $ | 5,589 | | $ | 58 | | $ | (5) | | $ | 5,642 | Corporate notes / bonds | | | 22,788 | | | (1) | | | (57) | | | 22,730 | Money market funds | | | 5,135 | | | — | | | — | | | 5,135 | U.S. govt. agencies | | | 4,454 | | | 24 | | | (6) | | | 4,472 | U.S. treasuries | | | 756 | | | (4) | | | (1) | | | 751 | Total investment securities | | $ | 38,722 | | $ | 77 | | $ | (69) | | $ | 38,730 |
| | | | | | | | | | | | | Balance at December 31, 2025 | | | Acquisition
Cost | | | Accretion /
(Amortization) | | | Unrealized
Gain / (Loss) | | | Estimated
Fair Value | Commercial paper | | $ | 4,888 | | $ | 34 | | $ | — | | $ | 4,922 | Corporate notes / bonds | | | 24,063 | | | 96 | | | 2 | | | 24,161 | Money market funds | | | 5,287 | | | — | | | — | | | 5,287 | U.S. govt. agencies | | | 11,192 | | | 64 | | | 5 | | | 11,261 | U.S. treasuries | | | 4,881 | | | 11 | | | (1) | | | 4,891 | Total investment securities | | $ | 50,311 | | $ | 205 | | $ | 6 | | $ | 50,522 |
Accretion / (amortization) refers to the discounts and premiums incurred on bonds and notes purchased and are included within Interest income on the consolidated statements of operations and comprehensive loss. Accrued interest receivable related to the above investment securities amounted to $267 and $314 as of September 30, 2026 and December 31, 2025, respectively, and is included in Other receivables on the consolidated balance sheets. The contractual maturities of investment securities as of September 30, 2026, are as follows: | | | | | | | | | | Acquisition
Cost | | | Estimated
Fair Value | Original maturities of 90 days or less | | $ | 5,135 | | $ | 5,135 | Original maturities of 91-365 days | | | 32,837 | | | 32,845 | Original maturities of 366+ days | | | 750 | | | 750 | Total investment securities | | $ | 38,722 | | $ | 38,730 |
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