Shares of memory-chip maker Micron Technology were sliding on Thursday after two storage companies beat analysts' earnings targets, but not by enough to win over Wall Street.

Micron stock slid 3.5% to $861.70 ahead of the opening bell, having closed pretty much flat the previous session. Futures tracking the S&P 500 were 0.2% higher.

Shares of memory-card supplier Sandisk were down 9%, hard-disk drive maker Western Digital slumped 14% in Thursday's premarket.

Both companies reported better-than-expected earnings late Wednesday, but didn't issue the sort of knockout guidance the market has come to expect as the AI buildout drives up memory demand.

Micron makes different products to Sandisk and Western Digital, but the three momentum stocks tend to trade in tandem.

Micron shares have soared almost 700% from a year ago, but it has dipped 10% over the past month as investors question how long the AI spending boom can last.