10 Stocks Lost Over 40% in 2026 as Investors Dumped Everything AI Might Kill

The S&P 500 rose 8.28% this year. However, ten of its own stocks lost more than 40%.

Both things are true at once. Investors are paying almost anything for AI. They are dumping whatever they think AI will kill.

AI Fear Crushed Software and Consulting Stocks

The damage is concentrated. Software, consulting and advertising names fill the bottom of the Slickcharts list.

It started in February. Anthropic released a new AI model. Enterprise software stocks sold off hard. Traders called it the SaaS-pocalypse.

Intuit (INTU) is the clearest victim, down 55.27%. It owns TurboTax, which brings in about a quarter of company revenue and profit.

Intuit (INTU) Stock Performance. Source: Google Finance

Then cheap AI tax tools arrived. Goldman Sachs analyst Gabriela Borges cut her price target in June to $276, down from $519.

Intuit moved fast. It cut 17% of staff, roughly 3,000 jobs. It also lowered its TurboTax forecast.

The company is now worth about $88 billion, Forbes reported. A year earlier it was worth more than $219 billion.

Accenture (ACN) tells a similar story, down 45.21%. Clients are spending on AI instead of consultants.

New client orders slipped to $19.3 billion from $19.7 billion. Accenture cut its sales growth forecast to between 3% and 4%. The stock fell almost 18% in one day.

Cognizant (CTSH), Gartner (IT) and The Trade Desk (TTD) each lost 44% to 55%. All three sell work that AI can copy.

S&P 500 worst-performing stocks of 2026 so far1. CoStar: -58.86%2. Intuit: -55.27%3. Trade Desk: -54.45%4. Boston Scientific: -53.59%5. Cognizant: -45.24%6. Accenture: -45.21%7. Lululemon: -45.01%8. Gartner: -44.31%9. Insulet: -42.56%10. AppLovin Corp: -41.83% pic.twitter.com/n8spGUcoOP

— Bull Theory (@BullTheoryio) July 26, 2026

But the Two Biggest Losers Had Nothing to do with AI

Here is the twist. The two worst stocks fell for old-fashioned reasons.

AI Fear Wiped 40% Off 10 S&P 500 Stocks While the Index Rose 8%

CoStar Group (CSGP) is down 58.86%, the weakest in the index. Its problem is spending, not AI.

CoStar owns Homes.com, a property listings site. In January it said the site will not cover its own costs until 2029. Profit is not expected until 2030.

The core business is fine. Revenue jumped 23% to $897 million last quarter. Profit was just $3 million.

Investors lost patience. In February, hedge fund D.E. Shaw told CoStar to quit or shrink Homes.com. It said the move could unlock more than $10 billion. CoStar called the campaign “activism malpractice.”

Shareholders backed the board in June. Nasdaq had already dropped the stock from its Nasdaq-100 index in May.

Boston Scientific (BSX) is down 53.59%. It simply grew slower than promised.

In February it expected sales to grow 10% to 11%. By April it cut that to between 6.5% and 8%.

A rival explains why. Medtronic said its heart device sales rose 124% in the United States. It took “an additional 8 points of U.S. share.”

Then bad news piled up. Boston Scientific recalled its Accolade pacemakers. Regulators tied the fault to four deaths and 2,557 serious injuries. It also agreed to buy Penumbra for $14.5 billion.

Where the Money Went Instead

Chip and memory makers took it. Sandisk (SNDK) is up 505.17% this year. Dell Technologies (DELL) rose 247.55%. Micron Technology (MU) gained 222.68%.

Sandisk (SNDK), Dell Technologies (DELL), and Micron Technology (MU) Stock Performances. Source: TradingView

Small investors piled in too, feeding the AI capex boom through chip funds. A narrow group of winners now drives the whole index, as data on AI stocks driving gains shows.

Everything else got punished for any slip. Expensive stocks fell hardest when forecasts came down, a danger flagged in recent earnings bubble warnings.

CoStar and Boston Scientific both report results this week. Those numbers will show whether investors were right or just impatient.