By Mackenzie Tatananni
British mathematician Clive Humby said it best when he proclaimed that data were the new oil. Nearly two decades later, the statement rings true.
Artificial intelligence was the foremost theme dominating 2025. The technology has driven massive demand for data storage products and memory chips, which has been a boon to certain stocks, including the top three performers in the S&P 500.
Western Digital dominated the benchmark index this year. By all accounts, the company had a blowout 2025, with shares exploding 291% on the back of ramping demand for its hard drives. Western Digital is best known as a major supplier of traditional hard disk drives, used for high-capacity data storage.
The steep gains become even more impressive considering Western Digital's market capitalization of $61.4 billion. It means the upswing in the stock price can be chalked up to more than volatility and speaks to the company's dominance in its industry.
Micron Technology is another name that crushed 2025, gaining nearly 248%. The memory-chip maker posted better-than-expected earnings for its quarter ended in November and issued guidance that handily topped expectations to cap off a stellar year.
Seagate Technology Holdings surged nearly 225% in 2025. Demand has exploded for Seagate's highest-capacity, highest-margin drives on the back of the data-center buildout. Seagate CEO Dave Mosley told Barron's earlier this month that the advent of AI had boosted the economic value of data and fundamentally reshaped hard drive demand.
Another name worth mentioning is Sandisk. The stock has only been in the S&P 500 for about a month, yet has gained almost 600% in 2025. Sandisk was spun off from Western Digital in February. While Sandisk soared during the year, it's not being considered the S&P 500's best stock since it only joined the index in November.
It wasn't a stellar year for every company. Shares of Trade Desk, an advertising-technology company, cratered 68% in 2025. The stock experienced a 40% drop after earnings in August, when the company issued a cautionary outlook for the third quarter. And that wasn't all: Fears of ramping competitive pressure from Amazon.com has weighed on shares, coupled with broader macroeconomic concerns.
Fiserv is laggard whose shares have slumped 67% this year. The fintech's troubles began in earnest in late October. Shares sank 44% after Fiserv halved its top-line growth forecast and slashed its earnings outlook, saying its operations in Argentina would be hurt by decaying economic conditions.
The inflation in Argentina that once benefited Fiserv has since cooled, and the company also has struggled with operational missteps. On Oct. 29, the stock closed below $100 for the first time since 2023. It has yet to rebound to those levels.
Alexandria Real Estate Equities was another straggler in 2025, with shares of the real estate investment trust falling 49%. The REIT was one of the index's worst performers in October after swinging to a loss in the third quarter and issuing an underwhelming full-year outlook.
On Dec. 3, Alexandria Real Estate Equities declared a dividend of 72 cents a share for the fourth quarter, or a 45% reduction from its third-quarter dividend, which the company framed as part of a broader attempt to strengthen its balance sheet.
Write to Mackenzie Tatananni at mackenzie.tatananni@barrons.com
This content was created by Barron's, which is operated by Dow Jones & Co. Barron's is published independently from Dow Jones Newswires and The Wall Street Journal.
(END) Dow Jones Newswires
December 31, 2025 07:55 ET (12:55 GMT)
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