| Schedule of Available-for-Sale Securities by Significant Investment Category |
As of December 31, 2025 and 2024, the Company has the following investments in available-for-sale debt securities, which are categorized as marketable securities: available-for-sale debt securities on the balance sheet depending on their maturity at acquisition (in thousands): | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | December 31, 2025 | | | Remaining contractual maturity | | Amortized cost | | Gross unrealized gains | | Gross unrealized losses | | Aggregate estimated fair value | Marketable securities: available-for-sale debt securities: | | | | | | | | | | | Commercial paper | | within 1 year | | $ | 52,569 | | | $ | 21 | | | $ | (1) | | | $ | 52,589 | | | Corporate debt securities | | within 1 year | | 58,226 | | | 74 | | | (1) | | | 58,299 | | United Kingdom Government Securities | | within 1 year | | 66,162 | | | 12 | | | — | | | 66,174 | | United States Treasury Bills | | within 1 year | | 19,466 | | | 50 | | | — | | | 19,516 | | | | | | | | | | | | | | | | | | | | | | | | Total | | | | $ | 196,423 | | | $ | 157 | | | $ | (2) | | | $ | 196,578 | |
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | December 31, 2024 | | | Remaining contractual maturity | | Amortized cost | | Gross unrealized gains | | Gross unrealized losses | | Aggregate estimated fair value | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Marketable securities: available-for-sale debt securities: | | | | | | | | | | | Commercial paper | | within 1 year | | $ | 21,145 | | | $ | 3 | | | $ | (7) | | | $ | 21,141 | | | Corporate debt securities | | within 1 year | | 91,853 | | | 5 | | | (70) | | | 91,788 | | United Kingdom Government Securities | | within 1 year | | 141,376 | | | — | | | (69) | | | 141,307 | | | | | | | | | | | | | US Treasury Bills | | within 1 year | | 29,663 | | | 12 | | | — | | | 29,675 | | | Corporate debt securities | | 1 to 5 years | | 59,530 | | | — | | | (194) | | | 59,336 | | US Treasury Bills | | 1 to 5 years | | 17,393 | | | 7 | | | (4) | | | 17,396 | | Total | | | | $ | 360,960 | | | $ | 27 | | | $ | (344) | | | $ | 360,643 | |
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| Schedule of Amount of Gross Unrealized Losses and Estimated Fair Value for Available-for-Sale Securities in an Unrealized Loss Position by Length of Time |
The number of securities held by the Company and aggregate fair value (in thousands) and in an unrealized loss position as of December 31, 2025 are as follows (in thousands): | | | | | | | | | | | | | | | | | | | | | | | December 31, 2025 | | | Number of securities held | | Gross unrealized losses | | Fair market value of investments in an unrealized loss position | Marketable securities: available-for-sale debt securities in a continuous loss position for less than 12 months: | | | | | | | | Commercial paper | | 2 | | $ | (1) | | | $ | 2,454 | | | Corporate debt securities | | 2 | | (1) | | | 7,000 | | | | | | | | | | | | | | | | Total | | 4 | | $ | (2) | | | $ | 9,454 | |
| | | | | | | | | | | | | | | | | | | | | | | December 31, 2024 | | | Number of securities held | | Gross unrealized losses | | Fair market value of investments in an unrealized loss position | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Marketable securities: available-for-sale debt securities in a continuous loss position for less than 12 months: | | | | | | | | Commercial paper | | 3 | | $ | (6) | | | $ | 8,944 | | | Corporate debt securities | | 41 | | (264) | | | 133,078 | | United Kingdom Government Securities | | 8 | | (69) | | | 141,307 | | | | | | | | | US Treasury Bills | | 4 | | (4) | | | 9,905 | | Total | | 56 | | $ | (343) | | | $ | 293,234 | |
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