In just under four weeks, the stocks that powered the AI boom gave back about $5 trillion in market value. That is roughly the size of Apple, the world’s most valuable company, wiped off 47 stocks. Yet the strangest part of October is that most of Wall Street had a decent month. Now investors head into one of the busiest weeks of the year: Apple earnings on Monday, the US midterm elections on Tuesday and the October jobs report on Friday.
Quick answer: According to Yahoo Finance calculations, the 47 biggest AI and chip stocks lost about $5 trillion in market value between 6 October and the end of October 2026, led by Nvidia and Alphabet (about $835 billion each). The trigger was growing doubt over whether huge AI spending will pay off, made worse by Intel’s weak forecast and a near-$500 billion one-day drop in Alphabet. Meanwhile, the other 625 large US stocks gained about $1.3 trillion. Stock futures bounced on Sunday night ahead of Apple earnings, the midterms and Friday’s jobs report.
What happened to AI stocks in October
Yahoo Finance tracked 47 of the largest AI and semiconductor stocks from 6 October onward. Together they lost roughly $5 trillion. The damage was concentrated at the top:
| Company | Approx. market value lost since 6 Oct | Note |
|---|---|---|
| Nvidia | ~$835 billion | Fell about 4% on Friday alone |
| Alphabet (Google) | ~$835 billion | Lost nearly $500 billion in a single day after earnings |
| SpaceX | ~$505 billion | Included in Yahoo’s AI and chip group |
| TSMC | ~$395 billion | World’s largest contract chipmaker |
| Intel | Nearly half its value in October | Down about 29% on Friday after its forecast |
The Nasdaq 100 fell about 3.5% on Friday and the S&P 500 about 1.8%. The iShares Semiconductor ETF (SOXX), a popular way to track chip stocks, dropped about 17% in October, although it is still up more than 50% for the year.
The rest of the market quietly rose
Here is the twist. While those 47 stocks were sliding, the other 625 large US companies in Yahoo’s tally added about $1.3 trillion in value. Last week the S&P 500 slipped about 0.6%, but 9 of its 11 sectors rose by around 1% or more. Yahoo Finance said no other down week since at least 1999 had more than seven sectors rising that much. In plain terms: this was a sell-off in AI and chips, not a broad market crash.
Why AI stocks fell: the spending question
The core worry is simple. Big Tech is spending staggering sums on data centres, chips and power, and investors are starting to ask when that money comes back. JPMorgan Global Research expects tech giants to spend about $900 billion on AI this year. Several reports in the final week of October sharpened those doubts:
- Alphabet: weaker-than-hoped revenue on Wednesday led to a loss of nearly $500 billion in market value the next day, which Forbes called the second-worst one-day drop in stock market history. We covered that report in detail in why Google stock fell after Alphabet’s Q3 earnings.
- Intel: forecast current-quarter revenue of $15 billion to $16 billion, below the roughly $17 billion analysts expected, and warned that its “significant, long-term and inherently risky investments” may not produce a favourable return. The stock fell 29% at Friday’s open.
- Amazon: revenue of $201.9 billion slightly missed estimates even as cloud revenue grew 39% to $46 billion. Quarterly capital spending hit $77.3 billion.
- Meta and Tesla: Meta spent $34.91 billion on capex in the quarter and set 2026 spending at $135 billion to $145 billion. Tesla cut its full-year capex guidance to $20 billion from more than $25 billion.
Interest rates added pressure. The Federal Reserve held rates steady on Wednesday, but two officials voted for a hike. Bank of America strategist Michael Hartnett has pointed to 42 central bank rate hikes worldwide over the past six months and argued investors should stay “risk-off until global rate hike ends.” The power squeeze behind AI growth is another long-running concern, which we explained in AI data centres hit a power wall.
Stock market today: futures bounce
On Sunday evening US time, stock futures pointed higher. Yahoo Finance’s snapshot showed S&P 500 futures up about 0.5%, Nasdaq futures up about 0.9% and Dow futures up about 0.4%. The 10-year Treasury yield eased to about 4.93% and the VIX volatility index slipped below 19. Oil helped: WTI crude, which settled above $104 a barrel on Friday, opened sharply lower after OPEC+ held its December output targets steady. Oil remains elevated with the Strait of Hormuz still effectively shut in the ninth month of the Iran war.
The monster week ahead
| Day (2026) | Event | Why it matters |
|---|---|---|
| Monday, 2 Nov | Apple Q4 earnings after the close (results 4:30pm ET, call 5pm ET); Palantir also reports | Apple is now the world’s most valuable company; Palantir is a bellwether for AI software |
| Tuesday, 3 Nov | US midterm elections | Control of Congress shapes tax, spending and regulation |
| Friday, 6 Nov | October jobs report | A key input for the Fed after two officials voted to hike |
Apple: the stock that escaped the rout
Apple closed Friday worth about $5.03 trillion, ahead of Nvidia at about $4.93 trillion. It is the only “Magnificent Seven” stock beating the S&P 500 this year, up about 27% against roughly 11% for the index. Analysts expect fiscal fourth-quarter revenue of about $113.3 billion and earnings of $1.99 per share, near the top of Apple’s guidance of $111.7 billion to $113.7 billion. Watch the iPhone 18 numbers, gross margins under pressure from rising memory prices, and the outlook for the December quarter, where the consensus sits near $153.4 billion.
Is a rebound coming? What history says
Jeff Hirsch, editor of the Stock Trader’s Almanac, has called the October slide “Octoberphobia” and argues the damage is less severe than headlines suggest. His reasoning is seasonal. In the US presidential cycle, the period from the fourth quarter of a midterm year through the following June has historically been the market’s “sweet spot”:
- From the last October close of a midterm year to the end of the next June, the S&P 500 has risen 19 out of 19 times since 1950, with a median gain of about 15%.
- Chip stocks have risen 8 out of 8 times since 1994 over the same window, with a median gain of about 22%.
- November is historically the S&P 500’s best month of the year.
There are important caveats. Eight cycles is a small sample. In 2002 and 2018, chips fell roughly another 11% before turning higher. Hirsch says he would change his view if the S&P 500 decisively breaks its mid-September low near 7,550, less than 1% below Friday’s close. Hartnett’s line in the sand for chips is $520 on the VanEck Semiconductor ETF (SMH), which closed Friday near $522. Both levels are close, so this week could decide which camp is right.
Disclaimer: This article is for information only and is not financial advice. Past market patterns do not guarantee future results. Speak to a qualified financial adviser before making investment decisions.
What it means for everyday investors
If you own a broad index fund, October probably felt calmer than the headlines, because gains across most other sectors offset much of the tech damage. If your portfolio leans heavily on AI and chip names, the month was far more painful, and the coming week matters more. The bigger story is a market that is starting to separate AI winners from AI spenders, rather than rewarding every company with an AI pitch. For another angle on how investors are pricing AI companies, see our look at the Anthropic IPO prospectus.
Frequently asked questions
How much did AI stocks lose in October 2026?
About $5 trillion in market value across 47 of the largest AI and chip stocks since 6 October, according to Yahoo Finance calculations.
Which stocks fell the most?
Nvidia and Alphabet each lost about $835 billion in value. SpaceX lost about $505 billion and TSMC about $395 billion. Intel lost nearly half its value during October.
Why did Intel stock crash?
Intel forecast current-quarter revenue of $15 billion to $16 billion, below the roughly $17 billion analysts expected, and warned its heavy investments may not produce a favourable return. Shares fell 29% at Friday’s open.
When does Apple report earnings?
Monday, 2 November 2026, after the market closes. Results are due at 4:30pm ET (1:30pm PT) with the conference call at 5pm ET.
Do stocks usually rise after the midterms?
Historically, yes. The S&P 500 has risen from the end of October in a midterm year to the following June every time since 1950, but past performance does not guarantee future returns.
Sources: Yahoo Finance, Forbes, iThinkDiff, Stock Trader’s Almanac (via Yahoo Finance), Bank of America research (via Yahoo Finance), Google Trends.
