Key Highlights

● The Philadelphia Semiconductor index closed at 10,688.80 on Friday, October 30, 2026.

● The drop was far steeper than the broader indexes.

● The SOX tracks large chip designers, makers and equipment suppliers.

● Selling spread across the industry.

The Philadelphia Semiconductor Index, often called the SOX, plunged to close at 10,688.80 on Friday, October 30, 2026, according to market data. The drop was far steeper than the declines in the major stock indexes, which themselves had their worst session since June.

The SOX tracks a group of large US-listed companies that design, make and Supply equipment for semiconductors. Its slide on Friday showed how widely the selling spread across the industry.

Intel lit the fuse

The trigger was Intel (NASDAQ:INTC). After the close on Thursday, the company guided fourth-quarter Revenue to $15 billion to $16 billion, below a consensus of about $17.1 billion to $17.3 billion, and warned it would burn cash this year. It cited a weak PC market tied to memory prices, Manufacturing bottlenecks and a factory accident in Israel.

Intel shares plunged to $65.76 on Friday. Market data said it was the steepest one-day drop on record, while other outlets called it the worst day since 1974.

Losses across the board

Most of the index's members fell steeply. Advanced Micro Devices (NASDAQ:AMD), Qualcomm (NASDAQ:QCOM) and Marvell Technology (NASDAQ:MRVL) tumbled. Nvidia (NASDAQ:NVDA), Broadcom (NASDAQ:AVGO) and Micron Technology (NASDAQ:MU) also fell sharply, and market data said Nvidia lost about $185 billion in market value. Equipment makers Applied Materials (NASDAQ:AMAT), Lam Research (NASDAQ:LRCX) and ASML (NASDAQ:ASML) declined as investors questioned the outlook for artificial-intelligence spending. Taiwan Semiconductor (NYSE:TSM)'s US-listed shares and Arm Holdings (NASDAQ:ARM) fell as well.

Qualcomm faced additional pressure from company-specific news, according to market data, including a new Patent license under which it pays Huawei and a renewed court fight with Arm. Memory stocks were hit hard: Sandisk (NASDAQ:SNDK) sank despite a strong quarter, as investors worried that memory prices may be peaking.

The selling reached companies that buy chips, too. PC makers Dell (NYSE:DELL) and HP tumbled after Intel said the PC slowdown could last into 2027. Hewlett Packard Enterprise (NYSE:HPE) and Super Micro Computer (NASDAQ:SMCI) also fell. Smaller semiconductor stocks such as Tower Semiconductor, Astera Labs and Penguin Solutions declined with the sector.

There were few bright spots. Monolithic Power Systems rose in the morning after strong results and a raised outlook, though its closing move was not confirmed.

A bad month, too

Friday's drop capped a steep October for chip stocks. The SOX fell sharply over the month, according to market data. The Nasdaq-100 lost roughly $2 trillion in Market Value in October, according to market data, and the Nasdaq Composite posted its worst month since March 2025.

On Friday, the S&P 500 fell 140.32 points to 7,580.07, the Dow Jones Industrial Average dropped 572.25 points to 51,770.31 and the Nasdaq Composite lost 747.73 points to 25,437.00. The Nasdaq-100 closed at 28,384.85. Technology was the worst-performing sector, while energy, consumer staples, utilities and health care rose.

"The message from investors is becoming clearer: strong AI Demand is no longer enough on its own," said a senior market analyst, according to market data.

What to watch

Several chip-related reports are due soon. Super Micro Computer reports after the close on November 3, and Qualcomm reports on November 4. Apple (NASDAQ:AAPL)'s results on Monday, November 2, will offer a view on device demand.

Investors will also track whether Intel's PC warning shows up in other companies' guidance, and whether memory prices hold up. The October jobs report on Friday, November 6, and the Federal Reserve's December meeting will shape the broader backdrop for a sector that has become central to the market's direction.