| Marketable Securities |
Our cash equivalents and marketable securities are classified as “available-for-sale” debt securities. The following is a summary of cash equivalents and marketable securities as of January 26, 2020 and January 27, 2019: | | | | | | | | | | | | | | | | | | | | | | | | | | January 26, 2020 | | Amortized Cost | | Unrealized Gain | | Unrealized Loss | | Estimated Fair Value | | Reported as | | | | | | Cash Equivalents | | Marketable Securities | | (In millions) | Money market funds | $ | 7,507 |
| | $ | — |
| | $ | — |
| | $ | 7,507 |
| | $ | 7,507 |
| | $ | — |
| Debt securities issued by the United States Treasury | 1,358 |
| | — |
| | — |
| | 1,358 |
| | 1,358 |
| | — |
| Debt securities issued by United States government agencies | 1,096 |
| | — |
| | — |
| | 1,096 |
| | 1,096 |
| | — |
| Corporate debt securities | 592 |
| | — |
| | — |
| | 592 |
| | 592 |
| | — |
| Foreign government bonds | 200 |
| | — |
| | — |
| | 200 |
| | 200 |
| | — |
| Certificates of deposit | 27 |
| | — |
| | — |
| | 27 |
| | 27 |
| | — |
| Asset-backed securities | 1 |
| | — |
| | — |
| | 1 |
| | — |
| | 1 |
| Total | $ | 10,781 |
| | $ | — |
| | $ | — |
| | $ | 10,781 |
| | $ | 10,780 |
| | $ | 1 |
|
| | | | | | | | | | | | | | | | | | | | | | | | | | January 27, 2019 | | Amortized Cost | | Unrealized Gain | | Unrealized Loss | | Estimated Fair Value | | Reported as | | | | | | Cash Equivalents | | Marketable Securities | | (In millions) | Corporate debt securities | $ | 2,626 |
| | $ | — |
| | $ | (6 | ) | | $ | 2,620 |
| | $ | 25 |
| | $ | 2,595 |
| Debt securities issued by United States government agencies | 2,284 |
| | — |
| | (4 | ) | | 2,280 |
| | — |
| | 2,280 |
| Debt securities issued by the United States Treasury | 1,493 |
| | — |
| | (1 | ) | | 1,492 |
| | 176 |
| | 1,316 |
| Money market funds | 483 |
| | — |
| | — |
| | 483 |
| | 483 |
| | — |
| Foreign government bonds | 209 |
| | — |
| | — |
| | 209 |
| | — |
| | 209 |
| Asset-backed securities | 152 |
| | — |
| | (1 | ) | | 151 |
| | — |
| | 151 |
| Mortgage backed securities issued by United States government-sponsored enterprises | 88 |
| | 1 |
| | — |
| | 89 |
| | — |
| | 89 |
| Total | $ | 7,335 |
| | $ | 1 |
| | $ | (12 | ) | | $ | 7,324 |
| | $ | 684 |
| | $ | 6,640 |
|
The unrealized losses as of January 26, 2020, aggregated by investment category and length of time that individual securities have been in a continuous loss position is not significant.
The gross unrealized losses are related to fixed income securities, temporary in nature, and driven primarily by changes in interest rates. We have the intent and ability to hold our investments until maturity. For fiscal years 2020, 2019, and 2018, there were no other-than-temporary impairment losses, and net realized gains/losses were not significant. The amortized cost and estimated fair value of cash equivalents and marketable securities as of January 26, 2020 and January 27, 2019 are shown below by contractual maturity. | | | | | | | | | | | | | | | | | | January 26, 2020 | | January 27, 2019 | | Amortized Cost | | Estimated Fair Value | | Amortized Cost | | Estimated Fair Value | | (In millions) | Less than one year | $ | 10,781 |
| | $ | 10,781 |
| | $ | 5,042 |
| | $ | 5,034 |
| Due in 1 - 5 years | — |
| | — |
| | 2,271 |
| | 2,268 |
| Mortgage-backed securities issued by United States government-sponsored enterprises not due at a single maturity date | — |
| | — |
| | 22 |
| | 22 |
| Total | $ | 10,781 |
| | $ | 10,781 |
| | $ | 7,335 |
| | $ | 7,324 |
|
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