| Marketable Debt and Equity Securities |
Marketable Debt and Equity Securities Marketable Debt Securities The Company’s marketable debt securities consisted of the following: | | | | | | | | | | | | | | | | | | | | | | | | | As of June 30, 2026 | | Amortized
Cost | | Gross
Unrealized
Gains | | Gross
Unrealized
Losses | | Fair Value | | (in thousands) | Money market funds | $ | 26,910 | | | $ | — | | | $ | — | | | $ | 26,910 | | | | | | | | | | Government securities | 442,549 | | | 167 | | | (1,029) | | | 441,687 | | | $ | 469,459 | | | $ | 167 | | | $ | (1,029) | | | $ | 468,597 | | | | | | | | | | | Reported as | | | | | | | | Cash equivalents | | | | | | | $ | 26,910 | | Marketable debt securities | | | | | | | 441,687 | | Total | | | | | | | $ | 468,597 | |
| | | | | | | | | | | | | | | | | | | | | | | | | As of December 31, 2025 | | Amortized
Cost | | Gross
Unrealized
Gains | | Gross
Unrealized
Losses | | Fair Value | | (in thousands) | Money market funds | $ | 35,565 | | | $ | — | | | $ | — | | | $ | 35,565 | | Corporate securities | 11,966 | | | 2 | | | — | | | 11,968 | | Government securities | 543,208 | | | 1,584 | | | — | | | 544,792 | | | $ | 590,739 | | | $ | 1,586 | | | $ | — | | | $ | 592,325 | | | | | | | | | | | Reported as | | | | | | | | Cash equivalents | | | | | | | $ | 35,565 | | Marketable debt securities | | | | | | | 556,760 | | Total | | | | | | | $ | 592,325 | |
The following table summarizes the contract maturities of the Company’s marketable debt securities as of June 30, 2026: | | | | | | | | | | | | | Amortized
Cost | | Estimated
Fair Value | | (in thousands) | | Mature in one year or less | $ | 333,146 | | | $ | 333,152 | | | Mature within two years | 109,403 | | | 108,535 | | Total | $ | 442,549 | | | $ | 441,687 | |
The Company did not record any allowance for credit losses on its marketable debt securities during the three and six months ended June 30, 2026 and 2025. Marketable Equity Securities The Company’s marketable equity securities consisted of the following: | | | | | | | | | | | | | June 30, 2026 | | December 31, 2025 | | (in thousands) | | | | | | | | | | Zenas BioPharma, Inc. | $ | 78,637 | | | $ | 112,502 | | | $ | 78,637 | | | $ | 112,502 | |
Net realized and unrealized gains (losses) on marketable equity securities, recognized in other income (expense) in the consolidated statements of operations and comprehensive loss, were as follows: | | | | | | | | | | | | | | | | | | | | | | | | | Three Months Ended
June 30, | | Six Months Ended
June 30, | | 2026 | | 2025 | | 2026 | | 2025 | | (in thousands) | | Total gains (losses) recorded on marketable equity securities | $ | 18,064 | | | $ | 4,967 | | | $ | (33,865) | | | $ | 5,908 | | | Less: (losses) gains recorded on sale of marketable equity securities | — | | | (12) | | | — | | | 5,380 | | | Unrealized gains (losses) on securities held at the reporting date | $ | 18,064 | | | $ | 4,979 | | | $ | (33,865) | | | $ | 528 | |
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