Key Highlights

● Micron fell below $900 on October 22 as memory stocks sank in the AI selloff.

● Micron makes DRAM and NAND memory chips, including high-bandwidth memory for AI processors.

● Seagate closed at $642.14 and Western Digital fell before reporting after the bell.

● Western Digital reported adjusted earnings of $4.64 a share against $4.08 expected.

Micron Technology (NASDAQ:MU) sank on Thursday, October 22, 2026, falling below $900 as memory stocks fell hard in the AI selloff that dragged down the S&P 500. The stock closed with a steep decline, after a smaller drop earlier in the session. The company put out no company-specific news.

Micron makes DRAM and NAND memory chips, including the high-bandwidth memory used alongside AI processors in data centers. That has made it one of the biggest winners of the AI build-out, and one of the most exposed when sentiment turns.

Memory and storage under pressure

Micron was part of a wider retreat in memory and storage. Sandisk (NASDAQ:SNDK) fell sharply. Seagate Technology (NASDAQ:STX) tumbled and closed at $642.14. Western Digital (NASDAQ:WDC) fell in the regular session before reporting results after the bell.

The Philadelphia Semiconductor Index had its biggest one-day drop since June 23, according to market data. It closed just above its 200-day moving average.

What triggered the slide

Two reports on Wednesday evening set the tone. Lam Research (NASDAQ:LRCX), a supplier of chipmaking equipment, reported record revenue of $8.22 billion and adjusted earnings of $2.20 a share. But its December-quarter guidance of $8.6 billion, plus or minus $400 million, had a midpoint slightly below consensus, and it cited supply constraints. Lam also said China sales would be "meaningfully down."

"Things are going to continue to be constrained," Lam's chief financial officer said. Lam's chief executive said clean-room and component constraints will "limit chip makers and equipment companies' ability to fully meet end demand" into 2027.

Meta Platforms (NASDAQ:META) narrowed its 2026 capital spending range to $135 billion to $145 billion and posted negative free cash flow of $2.12 billion, which marked its first cash outflow in more than a decade.

Nvidia (NASDAQ:NVDA)'s chief executive then said, "The demand of the capital is much greater than the availability of the capital." Nvidia closed at $212.21 and was one of the biggest drags on the S&P 500, according to market reports.

Market snapshot

The S&P 500 fell 93.74 points to 7,663.43, its worst day since July. The Nasdaq Composite tumbled 694.00 points to 26,008.86, its steepest drop since June 5, and lost about $1 trillion in market value, according to market data. The Dow Jones Industrial Average edged up 11.89 points.

About two of every three S&P 500 stocks rose, according to market reports. Staples had their best day since April 2025 and hit a record, health care set a record, and the 10-year Treasury yield fell back below a closely watched threshold for the first time since September 22.

Micron Looks to Western Digital for the First Read

Western Digital's results offer the first read. After the bell it reported adjusted earnings of $4.64 a share against $4.08 expected and guided next-quarter revenue to $5.0 billion to $5.2 billion, but its shares swung in after-hours trading, with an early gain erased.

Intel (NASDAQ:INTC) reports on October 29, according to the earnings calendar, and the hyperscalers follow, with Microsoft (NASDAQ:MSFT) and Alphabet (NASDAQ:GOOGL) on October 28 and Amazon (NASDAQ:AMZN) on October 29. Their spending on AI servers drives demand for high-bandwidth memory.

The Federal Reserve announces its rate decision on October 28.