The Puzzle Pieces for an AI Bubble-Bursting Event Are Falling Into Place

The Puzzle Pieces for an AI Bubble-Bursting Event Are Falling Into Place

Sean Williams, The Motley Fool

Thu, September 17, 2026 at 12:26 PM GMT+3 4 min read

For the better part of the last four years, artificial intelligence (AI) has been Wall Street's leading catalyst. Empowering software and systems with the tools to make autonomous, split-second decisions is a multitrillion-dollar global addressable opportunity that's lifted the Dow Jones Industrial Average (DJINDICES:^DJI), S&P 500 (SNPINDEX:^GSPC), and Nasdaq Composite (NASDAQINDEX:^IXIC) to new heights.

While it's easy to look at AI growth estimates and assume there's no end in sight to the infrastructure build-out, this would probably be a mistake. Based on several historical factors, the puzzle pieces for an AI bubble-bursting event appear to be falling into place.

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Game-changing technologies seemingly always endure early-stage bubbles

The historical puzzle piece that arguably hasn't moved for years is the idea of game-changing technologies enduring early-innings bubble-bursting events. For more than three decades, every major tech innovation, including the internet, eventually dove off the proverbial precipice.

The reason these bubbles form is that investors consistently overestimate the pace of adoption and/or optimization of game-changing technologies. While the otherworldly spending on the AI data center build-out indicates that there isn't an adoption problem, it'll likely take years before businesses understand how to optimize AI solutions to maximize sales and profits.

Don't forget, internet-driven businesses didn't truly mature until several years after the dot-com bubble burst.

Persistently elevated inflation can stop the music on Wall Street

Another puzzle piece that threatens to bring the AI revolution to a grinding halt is persistently elevated inflation.

In addition to President Donald Trump's tariffs and the Iran war driving up consumer prices, the Federal Open Market Committee (FOMC) has specifically labeled the AI infrastructure build-out as inflationary. Although the overwhelming demand for AI hardware and persistent supply shortages are boosting the pricing power of AI-based businesses, the downside is that higher prices are working their way down the chain to consumers.

The most logical way to deal with persistently elevated and entrenched inflation is for the FOMC to raise interest rates. But making borrowing costlier for a technological revolution that's been financed in part by debt can reset growth and valuation expectations.

Statistically, AI/stock market valuations aren't sustainable

While the argument can be made that aggressive AI growth expectations support premium valuations, history has a knack for foreshadowing trouble on Wall Street.

According to the S&P 500's Shiller Price-to-Earnings (P/E) Ratio, also known as the Cyclically Adjusted P/E Ratio (CAPE Ratio), this is the second-priciest stock market in history, thanks to AI. The previous five times that the Shiller P/E Ratio surpassed 30 were eventually followed by declines in the Dow, S&P 500, and/or Nasdaq Composite of 20% or considerably more. In short, premium valuations aren't sustainable over long periods.

Furthermore, select AI leaders sport price-to-sales (P/S) ratios that aren't historically tenable. History tells us that trailing 12-month P/S ratios above 30 for companies at the forefront of next-big-thing trends are indicative of bubbles. Elon Musk's Space Exploration Technologies (SpaceX) (NASDAQ:SPCX) and the developer of the Claude large language model, Anthropic, which is preparing for its initial public offering, both sport TTM P/S ratios that are well above this historical bubble threshold.

By all accounts, the puzzle pieces for an AI bubble-bursting event are falling into place.

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Sean Williams has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.

The Puzzle Pieces for an AI Bubble-Bursting Event Are Falling Into Place was originally published by The Motley Fool