This Tech Stock Takes the S&P 500 Top Spot in 2025

With traders dusting off their portfolios and reviewing their investment strategies for 2026, now is a good time to evaluate this year's outperformers to see if they still hold promise for the new year. We already covered the best Dow Jones Industrial Average stock of 2025 -- spoiler alert, it's not Nvidia (NVDA) -- so now the S&P 500 Index (SPX) gets the same treatment. 

Taking the benchmark's top spot for the year is Wall Street newbie SanDisk Corp (NASDAQ:SNDK), which began trading in early February and joined the SPX in late November. The flash memory manufacturing company is a spinoff of Western Digital (WDC), which takes the runner-up spot.

SNDK has added 268.2% in the last nine months, more than quadrupling off its independent trading debut on the Nasdaq at $36 on Feb. 13. Analysts were already taking notice before the rally picked up in September, culminating in a Nov. 12, record high of $284.59. Shares have since pulled back from that peak, but support at $200 appears to be keeping recent losses in check. 

Despite this outperformance, short sellers have been piling on the security, likely due to AI overvaluation concerns. Short interest is up 22.8% in the last two reporting periods, and now makes up more than 5.2% of the security's available float. This suggests SNDK may be a short squeeze contender in 2026.

It's also worth noting that the chip stock tended to outperform volatility expectations in the past year, as suggested by its Schaeffer's Volatility Scorecard (SVS) of 89 out of 100.