Why is Western Digital (WDC) stock up today?

Western Digital shares surged 12.51% to $548.39 today — well ahead of the broader market — as a powerful rally swept across the memory and storage sector. The move is part of a wider AI-fueled rebound in chip stocks, with peers Micron and SanDisk (SNDK) gaining 7% and 8% respectively on the same session, according to 24/7 Wall St. The rally reflects renewed investor enthusiasm for AI infrastructure demand, which drives heavy spending on the kind of NAND flash and hard-disk storage that Western Digital manufactures.

The catalyst is sector-wide: chip stocks surged broadly as investors shrugged off earlier fears about cheap Chinese large-language models and refocused on the sustained AI capital-expenditure cycle, per Yahoo Finance. SK Hynix and Micron led the charge, pulling memory and storage names — including Western Digital and SanDisk — along with the momentum. Western Digital and its recently spun-off SanDisk unit both appeared prominently in Barron's roundup of the stocks explaining Tuesday's market action.

Western Digital's own fundamentals add context. The company beat earnings estimates in its most recent quarter, reporting EPS of $2.72 against a consensus estimate of $2.39, on revenue of $3.34 billion. That underlying strength makes the stock receptive to a sector tailwind: when the memory rebound accelerates, a company that has already demonstrated it can beat on earnings tends to attract outsized buying interest.

The broader market also provided a supportive backdrop: the S&P 500 rose 0.89% and the tech-heavy QQQ ETF gained 1.85% on the session. Western Digital's move — roughly 14 times the S&P 500's gain — signals that today's surge is driven primarily by memory-sector and AI-demand dynamics rather than general market conditions. With the next earnings report due August 5, attention will turn to whether management's guidance confirms the demand rebound the market is pricing in.