Three years ago, OpenAI released ChatGPT, setting off a mania on Wall Street for all things artificial intelligence. And the stock market hasn’t been the same since. 

Bets that the groundbreaking technology will reshape society have minted new market leaders, made an already concentrated S&P 500 Index even more top heavy, and left companies and industries considered at risk of being replaced by AI struggling to keep pace. 

Yes, there are lingering concerns that the frenzy of spending tied to AI is unsustainable as big payoffs remain elusive. But investment in the technology has been the driving force behind the bull market in US stocks that began less then two months before ChatGPT debuted on Nov. 30, 2022 — and that doesn’t appear to be changing dramatically yet.

“Every bull market has a dominant theme, and the dominant theme of this bull market is technology and AI, and it really kicked off in earnest with the launch of ChatGPT,” said Keith Lerner, chief investment officer and chief market strategist at Truist Advisory Services. “If you believe we’re still in a bull market, which we do, you don’t want to give up too early on that leadership.”

Here’s a look at how AI has shaped the current market landscape.

Market Leaders

Expectations that the world’s largest technology companies would become the dominant players in AI helped revive Big Tech stocks that took a beating in 2022 amid falling profits and rising interest rates. 

“Any time in history AI growth would have driven a lot of these stocks up,” said Michael Bailey, director of research at Fulton Breakefield Broenniman. “But it started at a level of low expectations that has made the AI wave seem even more impressive.”

The rally sparked by AI enthusiasm has been the chief driving force behind the S&P 500’s 64% jump since the chatbot’s release. The seven most valuable companies in the S&P 500 — Nvidia Corp., Microsoft Corp., Apple Inc., Alphabet Inc., Amazon.com Inc., Meta Platforms Inc. and Broadcom Inc. — are all major players in the technology and account for nearly half of the benchmark’s gains over that time, according to data compiled by Bloomberg. 

Rise of Nvidia

No company has benefited from the explosion of investment in AI more than chipmaker Nvidia. With hundreds of billions of dollars being spent annually on computing equipment, its graphics processing units, which dominate the AI market, are experiencing seemingly insatiable demand. The stock is up 979% since the unveiling of ChatGPT, the third best performance in the S&P 500 over that time.

“If you had to quantify the AI product cycle, it’s all Nvidia, it’s all AI chips,” Bailey said.

Nvidia’s revenue is expected to exceed $200 billion this year, up from $27 billion at the end of calendar 2022, according to the average of analyst estimates compiled by Bloomberg. The company’s net income is projected to top $170 billion in the next 12 months, more than the combined anticipated profits of a third of the companies in the S&P 500.

Those lucrative prospects have also attracted increased competition in recent months. On Monday, The Information reported that Meta is in discussions to spend billions on Google’s AI chips, citing an unidentified person familiar with the matter. Nvidia shares fell on the report, while Alphabet jumped. 

Powering AI

While Big Tech’s dominant position in the race to build AI computing infrastructure may not be a surprise, the accompanying rally in electricity providers has been a bit of a shock. Vistra Corp.’s stock is up 620% in the past three years, making it the fourth-best performer in the S&P 500. NRG Energy Inc. and Constellation Energy Corp. have each gained more than 250% over that time. 

“I don’t think there’s a full appreciation for just how big of an impact this will have on their business in the future from a demand standpoint and just the staying power of that demand, specifically around the energy and utilities names,” said Matt Sallee, a portfolio manager at Tortoise Capital Advisors, which owns several AI energy stocks.

The thirst for power is so vast that tech giants are turning to new and old sources of energy. Nuclear startups like Nano Nuclear Energy and Oklo have soared in recent years. Constellation Energy has received $1 billion in backing from the US government for its plan to restart its Three Mile nuclear power plant, which was shuttered in 2019.

AI Wipeouts

The euphoria surrounding AI has put the focus on the technology’s winners, but its development has also created plenty of losers.

Fears about disruption have sparked a flight from companies that are perceived to be particularly at risk from AI. Those include software makers, staffing firms and even advertising agencies. A basket of such stocks put together by UBS has fallen by more than a third since ChatGPT’s release while the tech-heavy Nasdaq 100 Index has doubled.

“This particular tech wave and product cycle is coming on so fast, perhaps these companies just were unable to adapt to it,” Fulton Breakefield Broenniman’s Bailey said.

LivePerson Inc., a customer support software maker, and online education company Chegg Inc., have each sunk 97 per cent since Nov. 30, 2022. Staffing services companies ManpowerGroup Inc. and Robert Half Inc. have fallen more than 65 per cent.

Concentration

The Big Tech rally has made an already top-heavy stock market even more beholden to a small number of companies. The seven biggest firms in the S&P 500 now account for about 35% of the weighting in the market capitalization-based index, up from roughly 20% in late 2022.

This degree of concentration is unprecedented. And it’s raising concerns about risks to the broader market if this small collection of stocks start to struggle, said Gene Goldman, chief investment officer of Cetera Financial Group.

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Published on November 29, 2025