Key Highlights

● Storage and memory stocks rallied together on SK hynix's results.

● Micron, Sandisk and Seagate all climbed sharply.

● The storage surge was part of a wider semiconductor rally.

● The rally faced a cooldown after Alphabet's after-hours miss.

Storage, once one of the sleepier corners of the technology sector, is suddenly one of Wall Street's hottest trades, as Seagate Technology, Sandisk and Micron Technology all climbed, with investors betting that the AI boom will require ever more memory and storage capacity.

The rally was sparked by South Korea's SK hynix, which reported a more than sevenfold jump in profit and said it expects the memory shortage to last into 2030, according to reports, with quarterly revenue topping 100 trillion won for the first time, roughly $78.7 billion.

Who Rallied and Why

Micron, the largest US memory chipmaker, climbed strongly on the read-through, making DRAM and high-bandwidth memory used in AI accelerators. Sandisk, which focuses on flash storage, posted one of the strongest gains among the group, while Seagate, which makes hard drives, rose after reporting its own results.

The storage surge was part of a wider semiconductor rally, with the chip index rising for a fourth straight gain, as chip equipment makers Lam Research and Applied Materials both climbed, while Nvidia was an exception, slipping during the session.

The After-Hours Cooldown

The mood shifted after the closing bell, as Alphabet slid sharply in extended trading after missing estimates on both revenue and earnings, and Micron gave back ground after hours in sympathy, a reminder of how tightly storage stocks are tied to Big Tech's spending plans.

Not everyone is convinced the boom will last indefinitely, with one economist offering a longer-term warning about an eventual AI capex bust, though probably not for a few more years.