The summary of our investments in equity securities at May 31, 2024 and 2023 is as follows (in millions):


	2024		2023
Equity securities with readily determinable fair values	$	100	$	91
Equity securities without readily determinable fair values - NAV practical expedient		37		26
Equity securities without readily determinable fair values - measurement alternative		223		185
Total equity securities	$	360	$	302

Equity securities with a readily determinable fair value are Level 1 investments that are valued at the closing price or last trade reported on the major market on which the individual securities are traded. For equity securities without readily determinable fair values that qualify for the NAV practical expedient, we have elected to apply the NAV practical expedient to estimate fair value. We apply the measurement alternative for all other equity securities without readily determinable fair values, where adjustments to cost are made for observable price changes and any impairments. For equity securities where the measurement alternative is applied, annual and cumulative amounts of impairments, downward adjustments, and upward adjustments were immaterial for 2024 and 2023.

Unrealized gains and (losses) recognized during the reporting period on all equity securities still held at May 31, 2024, 2023, and 2022 were $14 million, ($48) million, and $60 million respectively.

The carrying values of our investments in debt securities are classified as available-for-sale and reported at their estimated fair values in our consolidated balance sheets and consisted of the following (in millions):


			Gross Unrealized
	Cost		Gains		Losses		Estimated Fair Value
May 31, 2024
Fixed-income securities	$	76	$	1	$	—	$	77
Total debt securities	$	76	$	1	$	—	$	77

Debt securities are Level 2 within the fair value hierarchy. This classification is defined as a fair value determined using market-based inputs other than quoted prices that are observable for the financial instruments, either directly or indirectly. Realized gains and losses were immaterial for 2024. We did not invest in debt securities during 2023.