Nasdaq Posts Worst Week Since June as AI Selloff and $110 Oil Rattle Wall Street

Why this matters: investors stopped asking how fast AI can grow and started asking how its huge buildout will be paid for

October 18, 2026 — The Nasdaq Composite fell about 4.5% for the week, its worst week since June, after a sharp Friday selloff in artificial-intelligence and chip stocks, while Brent crude settled at $109.86 a barrel and investors reassessed the debt behind the AI boom.

Image: Traders watch falling AI and chip stocks on Wall Street screens as oil prices rise in an editorial illustration. Credit: AI-generated illustration / Red Eye Eagle News, original illustration.

Editor's Highlight: This was not a selloff in every stock. The Dow Jones Industrial Average still gained about 0.7% for the week while the Nasdaq sank, showing a concentrated retreat from growth and AI-linked shares — and a rotation toward energy and other defensive areas — rather than a uniform market collapse.

Table of Contents

• Key Facts
• How the Week Ended on Friday
• CoreWeave and the AI Debt Question
• Chip Stocks Lead the Retreat
• Oil, Energy and the Other Side of the Trade
• Hedge Funds and the Global Spillover
• What Earnings and the Fed Must Now Show
• Bottom Line
• FAQ
• Sources

Key Facts

How the Week Ended on Friday

The S&P 500 lost about 1.9% for the week. Both the S&P 500 and the Nasdaq recorded their weakest week since June, according to the reports.

Newsroom Focus: The split between the Dow and the Nasdaq is the story in one line. Selling was heaviest where AI and growth valuations were highest.

CoreWeave and the AI Debt Question

CoreWeave, a data-center operator closely watched in the AI infrastructure trade, became the focal point of the week. Its shares fell about 12% on Friday, extending the weekly decline to about 25%.

Its bonds also came under pressure. Reuters reported that yields on its bonds pushed above 15%, a level that signals investors are demanding much higher compensation for risk.

That does not establish that default is inevitable. It does show how quickly the market question has changed, from demand for computing power to whether profits arrive in time to meet financial obligations.

Analysis Note: AI infrastructure needs chips, electricity and data centers at enormous cost. Strong demand alone does not guarantee attractive returns if borrowing costs keep rising.

Chip Stocks Lead the Retreat

Semiconductor shares were hit across the board on Friday. Broadcom fell 4.5%, Micron Technology lost 5.6% and Intel declined 5.8%, according to the reports.

The PHLX semiconductor index dropped 3.8%. Reports described it as an eighth consecutive daily decline and the longest such losing streak since 2008.

Oil, Energy and the Other Side of the Trade

Oil rose sharply at the same time technology fell. West Texas Intermediate futures settled 3.51% higher at $101.41 a barrel, according to a CNBC closing report cited in the coverage, while Brent advanced to $109.86.

Traders assessed supply risks linked to the Middle East. Higher oil can raise costs for fuel-dependent businesses while supporting energy producers.

"There is some fear in the market," Rob Haworth, senior investment strategist at U.S. Bank Wealth Management, told Reuters. He said expensive oil can weigh on the price investors are prepared to pay for corporate earnings.

Practical Takeaway: Sustained oil above $100 can feed into transport and consumer costs.

Hedge Funds and the Global Spillover

Goldman Sachs prime brokerage data, reported by Reuters, showed fundamental equity long-short strategies fell 2.9% in sessions ending October 15, while keeping a 14.3% year-to-date return. South Korea's KOSPI and Taiwan stocks also fell sharply during the week.

Bruno Schneller of Erlen Capital Management told Reuters this was less a rejection of AI than a high-velocity unwind of a crowded trade.

What Earnings and the Fed Must Now Show

Investors now turn to earnings. One report said analysts expected third-quarter earnings growth of more than 30%, based on LSEG data, with AI-related megacaps contributing heavily to that forecast.

Those are estimates, not reported results. Companies must show whether revenue and margins support remaining valuations.

The Federal Reserve meets on October 27-28. One report said futures pricing through CME's FedWatch tool assigned about an 82% probability to unchanged rates at the October meeting — a market estimate at a particular time, not a promise from policymakers.

Bottom Line

Wall Street's worst week since June for the Nasdaq was driven by a specific question, not a general collapse: can AI infrastructure spending produce enough cash flow to justify its debt and valuations when oil is above $100 and inflation is persistent?

Watch Monday's reopening, upcoming earnings, and whether chip stocks can break an eight-day losing streak.

FAQ

What happened to the Nasdaq this week?

The Nasdaq Composite fell about 4.5% for the week to 26,140.03, its worst week since June. It fell about 2.1% on Friday alone.

Why did AI stocks fall so sharply?

Investors questioned whether companies building AI infrastructure can earn enough, soon enough, to cover heavy borrowing costs. CoreWeave, down about 25% for the week with bond yields above 15%, became the clearest example in the reports.

Did every stock fall?

No. The Dow gained about 0.7% for the week, energy rose 2.47% on Friday and utilities rose 1.4%. The selling was concentrated in technology, chips and growth stocks.

Why did oil matter to stock investors?

Brent settled at $109.86 and WTI at $101.41. Higher oil raises business and household costs, can support energy shares, and can complicate inflation and interest-rate expectations.

When do markets reopen and what comes next?

The next scheduled U.S. session is Monday, October 19, from 9:30 a.m. EDT. Investors will watch earnings, oil, inflation and the Federal Reserve meeting on October 27-28.

Sources

• Yoopya News — Why Wall Street fell and what investors watch before Monday, with index closes, CoreWeave, oil and Fed details: https://www.yoopya.com/business/markets/wall-street-today-october-17-2026
• Eurasia Business News — Stock market today, AI selloff sends Wall Street to worst week since June, with chip and oil detail: https://eurasiabusinessnews.com/2026/10/17/stock-market-today-ai-selloff-sends-wall-street-to-worst-week-since-june/
• Catenaa — Global hedge funds suffer losses amid AI stock selloff, reporting Goldman Sachs prime brokerage data via Reuters: https://catenaa.com/markets/global-markets/global-hedge-funds-suffer-losses-amid-ai-stock-selloff/
• NewsNation Online — Nasdaq slides 2.1% as AI stocks weaken and oil prices rise, Wall Street recap: https://newsnationonline.com/news/nasdaq-falls-ai-stocks-oil-prices-wall-street-october-16-2026/
• Image source — Original AI-generated illustration created for Red Eye Eagle News for this article.