The following tables summarize the Company's investments in available-for-sale debt securities by significant investment category and the related consolidated balance sheet classification at April 24, 2020 and April 26, 2019:


	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


	April 26, 2019
	Valuation												Balance Sheet Classification
(in millions)	Cost		Unrealized Gains		Unrealized Losses		Fair Value		Investments		Other Assets
Level 1:
U.S. government and agency securities	$	529	$	1	$	(7)	$	523	$	523	$	—
Level 2:
Corporate debt securities	3,500		14		(21)		3,493		3,493		—
U.S. government and agency securities	387		1		(7)		381		381		—
Mortgage-backed securities	537		3		(20)		520		520		—
Non-U.S. government and agency securities	11		—		—		11		11		—
Other asset-backed securities	529		1		(3)		527		527		—
Total Level 2	4,964		19		(51)		4,932		4,932		—
Level 3:
Auction rate securities	47		—		(3)		44		—		44
Total available-for-sale debt securities	$	5,540	$	20	$	(61)	$	5,499	$	5,455	$	44

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 April 24, 2020 and April 26, 2019:


	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)


	April 26, 2019
	Less than 12 months						More than 12 months
(in millions)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
U.S. government and agency securities	$	130	$	(1)	$	649	$	(13)
Corporate debt securities	582		(5)		1,153		(16)
Mortgage-backed securities	73		(1)		250		(19)

Other asset-backed securities	290		(2)		85		(1)
Auction rate securities	—		—		44		(3)
Total	$	1,075	$	(9)	$	2,181	$	(52)

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. The Company’s policy is to recognize transfers into and out of levels within the fair value hierarchy at the end of the fiscal quarter in which the actual event or change in circumstances that caused the transfer occurs. There were no transfers between Level 1, Level 2, or Level 3 during fiscal years 2020 or 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.

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 other-than-temporary 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 April 24, 2020 and April 26, 2019, the credit loss portion of other-than temporary impairments on debt securities was not significant. No available-for-sale securities were sold for significantly less than carrying value during the fiscal years 2020 or 2019.

The April 24, 2020 balance of available-for-sale 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.


(in millions)	April 24, 2020
Due in one year or less	$	2,190
Due after one year through five years	2,854
Due after five years through ten years	1,733
Due after ten years	64
Total debt securities	$	6,841

The Company commonly 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 within 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.


(in millions)	April 24, 2020		April 26, 2019
Investments with readily determinable fair values (marketable equity securities)	$	18	$	—
Investments without readily determinable fair values	391		308
Equity method and other investments	71		64
Total equity and other investments	$	480	$	372

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.

Net losses recognized during fiscal year 2020 were $13 million, comprised of $15 million unrealized gains and losses on equity securities and other investments still held at April 24, 2020, and $2 million realized gains recognized on equity securities and other investments sold during the fiscal year. Net gains recognized during fiscal year 2019 were $104 million, comprised of $94 million net realized gains on equity and other investments sold during the period and $10 million of unrealized gains on equity and other investments still held at April 26, 2019. Gross gains and losses for fiscal year 2018 represent gains and losses on instruments sold during the period.

Impairment charges incurred on the Company's equity securities, equity method investments, and other investments during fiscal years 2020 and 2019 were not significant. During fiscal year 2018, the Company received bids from potential buyers and investors for some or all of its ownership in a portfolio of selected investments, which indicated that the fair values of certain of the underlying cost and equity method investments in the portfolio may be below the respective carrying values. The Company determined that the decline in the fair values was other-than-temporary given the uncertainty regarding the Company’s intent to hold the investments for a period of time that would be sufficient to recover the carrying values. As a result, the Company recognized impairment charges of $227 million during fiscal year 2018, which were recognized in other non-operating income, net in the consolidated statements of income. The fair values of the investments were determined based on Level 3 inputs. The