The S&P 500 gained 8.28% in 2026, but a handful of stocks got crushed. Ten companies in the index lost more than 40% of their value. The biggest losers were a mix of AI-fearing software firms and two non-tech names that stumbled for their own reasons.
AI fear hit software and consulting stocks hardest
Investors punished companies whose business models suddenly looked vulnerable to cheap AI tools. Intuit, the maker of TurboTax and QuickBooks, saw its stock fall 55.27% after cutting its forecast. The company blamed a shift to free or low-cost AI tax preparation software. Intuit also cut about 10% of its workforce — roughly 3,000 jobs — as part of a restructuring.
Goldman Sachs analyst Gabriela Borges slashed her price target on Intuit from $519 to $276 in June, citing the AI threat. The stock closed the year at $280, down from $627. Intuit’s market cap shrank from about $219 billion to $88 billion.
Accenture dropped 45.21%. The consulting giant reported that new bookings slipped to $19.3 billion from $19.7 billion a year earlier, and it trimmed its sales growth forecast to between 3% and 4%. Shares fell nearly 18% in a single day after the news. Cognizant, Gartner, and The Trade Desk each lost 44% to 55% as clients began using AI tools instead of hiring consultants.
CoStar Group: a real-estate bet gone wrong
The worst-performing S&P 500 stock in 2026 was CoStar Group, down 58.86%. Its Homes.com business is not expected to cover its own costs until 2029, and the company doesn’t expect profit from it until 2030. Revenue jumped 23% to $897 million, but profit was just $3 million.
Hedge fund D.E. Shaw urged CoStar to shut down or shrink Homes.com, arguing it could unlock more than $10 billion in shareholder value. CoStar called the campaign “activism malpractice.” Shareholders backed the board in June. Nasdaq dropped CoStar from its Nasdaq-100 index in May.
Boston Scientific: a recall and a rival’s surge
Boston Scientific lost 53.59%, the second-worst performance in the index. The medical device maker cut its sales growth forecast from 10-11% to 6.5-8% in April. Medtronic said its heart device sales rose 124% in the U.S., taking “an additional 8 points of U.S. share.”
Boston Scientific also recalled its Accolade pacemakers. Regulators tied the fault to four deaths and 2,557 serious injuries. The company agreed to buy Penumbra for $14.5 billion, a deal that hasn’t yet closed.
The winners: chip stocks and AI infrastructure
While some stocks cratered, others soared. Sandisk gained 505.17%, Dell Technologies rose 247.55%, and Micron Technology climbed 222.68%. Small investors piled into chip funds, feeding the AI capex boom that drove demand for data-center hardware and memory chips.
The question hanging over 2027 is whether the AI spending spree can keep lifting those winners — or whether the software rout is a warning that the boom has already peaked.
