| Summary of Marketable Securities |
As of January 31, 2022 and 2021, our marketable securities consisted of the following: | | | | | | | | | | | | | | | | | | | | | | | | | As of January 31, 2022 | | Amortized
Cost | | Gross
Unrealized
Gains | | Gross
Unrealized
Losses | | Estimated
Fair
Value | | | | | | | | | | (in thousands) | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commercial paper | $ | 28,723 | | | $ | — | | | $ | — | | | $ | 28,723 | | | Agency bonds | 632,935 | | | 2 | | | (3,328) | | | 629,609 | | | Corporate and other debt securities | 282,124 | | | 5 | | | (1,202) | | | 280,927 | | | U.S. government agency securities | 3,046,742 | | | 28 | | | (19,261) | | | 3,027,509 | | | Treasury bills | 389,826 | | | — | | | (148) | | | 389,678 | | | Marketable securities | $ | 4,380,350 | | | $ | 35 | | | $ | (23,939) | | | $ | 4,356,446 | |
| | | | | | | | | | | | | | | | | | | | | | | | | As of January 31, 2021 | | Amortized
Cost | | Gross
Unrealized
Gains | | Gross
Unrealized
Losses | | Estimated
Fair
Value | | | | | | | | | | (in thousands) | | | | | | | | | | | | | | | | | | Commercial paper | $ | 26,222 | | | $ | — | | | $ | — | | | $ | 26,222 | | | Agency bonds | 461,335 | | | 79 | | | (49) | | | 461,365 | | | Corporate and other debt securities | 465,207 | | | 1,113 | | | (64) | | | 466,256 | | | U.S. government agency securities | 834,894 | | | 28 | | | (257) | | | 834,665 | | | Treasury bills | 215,902 | | | 6 | | | (6) | | | 215,902 | | | Marketable securities | $ | 2,003,560 | | | $ | 1,226 | | | $ | (376) | | | $ | 2,004,410 | |
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| Summary of Contractual Maturities of Marketable Securities |
The following table presents the contractual maturities of our marketable securities as of January 31, 2022 and 2021: | | | | | | | | | | | | | As of January 31, | | 2022 | | 2021 | | | | | | (in thousands) | | Less than one year | $ | 2,387,139 | | | $ | 1,017,048 | | | Due in one to five years | 1,969,307 | | | 987,362 | | | Total | $ | 4,356,446 | | | $ | 2,004,410 | |
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| Investment Holdings, Schedule of Investments |
Strategic investments by form and measurement category as of January 31, 2022 were as follows: | | | | | | | | | | | | | | | | | | | | | | | | | Measurement Category | | Fair Value | | Measurement Alternative | | Equity Method | | Total | | | | | | | | | | (in thousands) | | Equity securities | $ | 168,784 | | | $ | 91,399 | | | $ | 93,400 | | | $ | 353,583 | | | Debt securities | 14,231 | | | — | | | — | | | 14,231 | | | Strategic investments | $ | 183,015 | | | $ | 91,399 | | | $ | 93,400 | | | $ | 367,814 | |
Strategic investments by form and measurement category as of January 31, 2021 were as follows: | | | | | | | | | | | | | | | | | | | | | | | | | Measurement Category | | Fair Value | | Measurement Alternative | | Equity Method | | Total | | | | | | | | | | (in thousands) | | Equity securities | $ | — | | | $ | 13,538 | | | $ | — | | | $ | 13,538 | | | Debt securities | 5,130 | | | — | | | — | | | 5,130 | | | Strategic investments | $ | 5,130 | | | $ | 13,538 | | | $ | — | | | $ | 18,668 | |
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