| Cash Equivalents and Marketable Securities |
The following is a summary of cash equivalents and marketable securities as of April 28, 2019 and January 27, 2019: | | | | | | | | | | | | | | | | | | | | | | | | | | April 28, 2019 | | Amortized Cost | | Unrealized Gain | | Unrealized Loss | | Estimated Fair Value | | Reported as | | | | | | Cash Equivalents | | Marketable Securities | | (In millions) | Corporate debt securities | $ | 2,899 |
| | $ | 2 |
| | $ | (2 | ) | | $ | 2,899 |
| | $ | 1,048 |
| | $ | 1,851 |
| Debt securities of United States government agencies | 1,882 |
| | — |
| | (1 | ) | | 1,881 |
| | — |
| | 1,881 |
| Debt securities issued by the United States Treasury | 1,833 |
| | — |
| | — |
| | 1,833 |
| | 932 |
| | 901 |
| Money market funds | 681 |
| | — |
| | — |
| | 681 |
| | 681 |
| | — |
| Foreign government bonds | 183 |
| | — |
| | — |
| | 183 |
| | — |
| | 183 |
| Asset-backed securities | 133 |
| | — |
| | (1 | ) | | 132 |
| | — |
| | 132 |
| Mortgage-backed securities issued by United States government-sponsored enterprises | 81 |
| | 1 |
| | — |
| | 82 |
| | — |
| | 82 |
| Total | $ | 7,692 |
| | $ | 3 |
| | $ | (4 | ) | | $ | 7,691 |
| | $ | 2,661 |
| | $ | 5,030 |
|
| | | | | | | | | | | | | | | | | | | | | | | | | | 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 of 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 following table provides the breakdown of unrealized losses as of April 28, 2019, aggregated by investment category and length of time that individual securities have been in a continuous loss position: | | | | | | | | | | | | | | | | | | | | | | | | | | Less than 12 Months | | 12 Months or Greater | | Total | | Estimated Fair Value | | Gross Unrealized Losses | | Estimated Fair Value | | Gross Unrealized Losses | | Estimated Fair Value | | Gross Unrealized Losses | | (In millions) | Debt securities issued by United States government agencies | $ | 1,429 |
| | $ | — |
| | $ | 306 |
| | $ | (1 | ) | | $ | 1,735 |
| | $ | (1 | ) | Corporate debt securities | 330 |
| | (1 | ) | | 453 |
| | (1 | ) | | 783 |
| | (2 | ) | Asset-backed securities | — |
| | — |
| | 132 |
| | (1 | ) | | 132 |
| | (1 | ) | Total | $ | 1,759 |
| | $ | (1 | ) | | $ | 891 |
| | $ | (3 | ) | | $ | 2,650 |
| | $ | (4 | ) |
The amortized cost and estimated fair value of cash equivalents and marketable securities as of April 28, 2019 and January 27, 2019 are shown below by contractual maturity. | | | | | | | | | | | | | | | | | | April 28, 2019 | | January 27, 2019 | | Amortized Cost | | Estimated Fair Value | | Amortized Cost | | Estimated Fair Value | | (In millions) | Less than 1 year | $ | 5,773 |
| | $ | 5,770 |
| | $ | 5,042 |
| | $ | 5,034 |
| Due in 1 - 5 years | 1,896 |
| | 1,898 |
| | 2,271 |
| | 2,268 |
| Mortgage-backed securities issued by United States government-sponsored enterprises not due at a single maturity date | 23 |
| | 23 |
| | 22 |
| | 22 |
| Total | $ | 7,692 |
| | $ | 7,691 |
| | $ | 7,335 |
| | $ | 7,324 |
|
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