The Company holds investments in marketable debt securities that are classified and accounted for as available-for-sale and held-to-maturity. Investments classified as available-for-sale are remeasured on a recurring basis. Investments classified as held-to-maturity are measured at amortized cost. The following tables summarize the Company's investments in available-for-sale and held-to-maturity debt securities by significant investment category and the related consolidated balance sheet classification at October 30, 2020 and April 24, 2020:


	October 30, 2020
	Valuation								Balance Sheet Classification
(in millions)	Cost		Unrealized Gains		Unrealized Losses		Fair Value		Investments		Other Assets
Available-for-sale securities:
Level 1:
U.S. government and agency securities	$	497	$	39	$	—	$	536	$	536	$	—
Level 2:
Corporate debt securities	4,234		124		(32)		4,326		4,326		—
U.S. government and agency securities	888		1		(1)		888		888		—
Mortgage-backed securities	661		27		(19)		669		669		—
Non-U.S. government and agency securities	36		1		—		37		37		—
Other asset-backed securities	518		4		(7)		515		515		—
Total Level 2	6,337		157		(59)		6,435		6,435		—
Level 3:

Auction rate securities	36		—		—		36		—		36

Total available-for-sale debt securities	6,870		196		(59)		7,007		6,971		36
Held-to-maturity securities:
Level 2:
Time deposit	886		—		—		886		886		—
Total debt securities	$	7,756	$	196	$	(59)	$	7,893	$	7,857	$	36


	April 24, 2020
	Valuation								Balance Sheet Classification
(in millions)	Cost		Unrealized Gains		Unrealized Losses		Fair Value		Investments		Other Assets
Level 1:
U.S. government and agency securities	$	542	$	47	$	—	$	589	$	589	$	—
Level 2:
Corporate debt securities	4,285		66		(90)		4,261		4,261		—
U.S. government and agency securities	746		1		—		747		747		—
Mortgage-backed securities	705		20		(28)		697		697		—
Non-U.S. government and agency securities	34		—		—		34		34		—
Other asset-backed securities	499		1		(20)		480		480		—
Total Level 2	6,269		88		(138)		6,219		6,219		—
Level 3:
Auction rate securities	36		—		(3)		33		—		33
Total available-for-sale debt securities	$	6,847	$	135	$	(141)	$	6,841	$	6,808	$	33

The following tables present the gross unrealized losses and fair values of the Company’s available-for-sale debt securities that have been in a continuous unrealized loss position deemed to be temporary, aggregated by investment category at October 30, 2020 and April 24, 2020:


	October 30, 2020
	Less than 12 months				More than 12 months
(in millions)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
U.S. government and agency securities	$	—	$	—	$	196	$	(1)
Corporate debt securities	5		—		858		(32)
Mortgage-backed securities	25		(3)		119		(16)

Other asset-backed securities	8		—		347		(7)

Total	$	38	$	(3)	$	1,520	$	(56)


	April 24, 2020
	Less than 12 months				More than 12 months
(in millions)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses

Corporate debt securities	$	1,368	$	(2)	$	2,893	$	(88)
Mortgage-backed securities	35		(1)		663		(27)

Other asset-backed securities	17		—		463		(20)
Auction rate securities	33		(3)		—		—
Total	$	1,453	$	(6)	$	4,019	$	(135)

The Company reviews the fair value hierarchy classification on a quarterly basis. Changes in the ability to observe valuation inputs may result in a reclassification of levels for certain securities within the fair value hierarchy. There were no transfers into or out of Level 3 during the three and six months ended October 30, 2020 and October 25, 2019. When a determination is made to classify an asset or liability within Level 3, the determination is based upon the significance of the unobservable inputs to the overall fair value measurement.

There were no purchases, sales, settlements, or significant gains or losses recognized in earnings or other comprehensive income for debt securities classified as Level 3 during the three and six months ended October 30, 2020 and October 25, 2019.


	Three months ended				Six months ended
(in millions)	October 30, 2020		October 25, 2019		October 30, 2020		October 25, 2019
Proceeds from sales	$	1,932	$	1,691	$	4,335	$	3,258
Gross realized gains	3		4		8		8
Gross realized losses	(1)		(4)		(7)		(12)

Credit losses represent the difference between the present value of cash flows expected to be collected on certain mortgage-backed securities and auction rate securities and the amortized cost of these securities. Based on the Company’s assessment of the credit quality of the underlying collateral and credit support available to each of the remaining securities in which the Company is invested, the Company believes it has recognized all necessary impairments, as the Company does not have the intent to sell, nor is it more likely than not that the Company will be required to sell, before recovery of the amortized cost. At October 30, 2020 and April 24, 2020, there were no debt securities in a credit loss position. No available-for-sale or held-to-maturity securities were sold for significantly less than carrying value during the three and six months ended October 30, 2020 and October 25, 2019.

The October 30, 2020 balance of available-for-sale and held-to-maturity debt securities by contractual maturity is shown in the following table. Within the table, maturities of mortgage-backed securities have been allocated based upon timing of estimated cash flows assuming no change in the current interest rate environment. Actual maturities may differ from contractual maturities because the issuers of the securities may have the right to prepay obligations without prepayment penalties.


	October 30, 2020
(in millions)	Available-For-Sale		Held-To-Maturity
Due in one year or less	$	1,930	$	886
Due after one year through five years	3,315		—
Due after five years through ten years	1,695		—
Due after ten years	67		—
Total	$	7,007	$	886

The Company holds investments in equity securities with readily determinable fair values, equity investments without readily determinable fair values, investments accounted for under the equity method, and other investments. Equity securities with readily determinable fair values are included in Level 1 of the fair value hierarchy, as they are measured using quoted market prices. Equity method investments and investments without readily determinable fair values are included within Level 3 of the fair value hierarchy due to the use of significant unobservable inputs to determine fair value. To determine the fair value of these investments, the Company uses all pertinent financial information available related to the investees, including financial statements, market participant valuations from recent and proposed equity offerings, and other third-party data.

The following table summarizes the Company's equity and other investments at October 30, 2020 and April 24, 2020, which are classified as other assets in the consolidated balance sheets:


(in millions)	October 30, 2020		April 24, 2020
Investments with readily determinable fair value (marketable equity securities)	$	25	$	18
Investments without readily determinable fair values	478		391
Equity method and other investments	74		71
Total equity and other investments	$	577	$	480

The table below includes activity related to the Company’s portfolio of equity and other investments. Gains and losses on equity and other investments are recognized in other non-operating income, net in the consolidated statements of income.


	Three months ended				Six months ended
(in millions)	October 30, 2020		October 25, 2019		October 30, 2020		October 25, 2019
Proceeds from sales	$	2	$	—	$	2	$	2
Gross gains	2		14		14		14
Gross losses	(2)		—		(2)		—
Impairment losses recognized	—		(2)		(2)		(3)