| Summary of Marketable Debt Securities |
The following tables summarize our marketable debt securities: | | | | | | | | | | | | | | | | | | | | | | | | | As of March 31, 2025 | | (In thousands) | Amortized
Cost | | Gross Unrealized Gains | | Gross Unrealized Losses | | Fair Value | | U.S. treasury securities | $ | 802,024 | | | $ | 1,646 | | | $ | (144) | | | $ | 803,526 | | | U.S. government-sponsored enterprise securities | 416,708 | | | 567 | | | (201) | | | 417,074 | | | Corporate notes | 372,040 | | | 813 | | | (117) | | | 372,736 | | | Commercial paper | 47,926 | | | — | | | — | | | 47,926 | | | | | | | | | | | Municipal securities | 5,000 | | | 10 | | | — | | | 5,010 | | | Total | $ | 1,643,698 | | | $ | 3,036 | | | $ | (462) | | | $ | 1,646,272 | |
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | As of December 31, 2024 | | | | | | (In thousands) | Amortized
Cost | | Gross Unrealized Gains | | Gross Unrealized Losses | | Fair Value | | | | | | U.S. treasury securities | $ | 957,145 | | | $ | 1,377 | | | $ | (467) | | | $ | 958,055 | | | | | | | U.S. government-sponsored enterprise securities | 405,890 | | | 575 | | | (370) | | | 406,095 | | | | | | | Corporate notes | 361,311 | | | 769 | | | (341) | | | 361,739 | | | | | | | Commercial paper | 58,117 | | | — | | | — | | | 58,117 | | | | | | | | | | | | | | | | | | | Municipal securities | 5,002 | | | 1 | | | — | | | 5,003 | | | | | | | Total | $ | 1,787,465 | | | $ | 2,722 | | | $ | (1,178) | | | $ | 1,789,009 | | | | | |
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| Summary of Fair Value of Marketable Debt Securities |
The fair values of our marketable debt securities by classification in the condensed consolidated balance sheets were as follows: | | | | | | | | | | | | | (In thousands) | As of March 31, 2025 | | As of December 31, 2024 | | Marketable debt securities | $ | 1,605,368 | | | $ | 1,719,920 | | | Cash and cash equivalents | 40,904 | | | 69,089 | | | Total | $ | 1,646,272 | | | $ | 1,789,009 | |
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