The U.S. stock market has surged dramatically in recent years, fueled largely by investor enthusiasm surrounding artificial intelligence technologies and their commercial potential.
AI stocks have led a powerful bull market now entering its third year, with companies across the chip design and cloud computing sectors posting extraordinary revenue growth.
The tech-heavy Nasdaq Composite has climbed 122% over the past three calendar years, while the S&P 500 (SPX) gained 78% over the same period.
The Dow Jones Industrial Average advanced 45% over three years and recently closed above 53,000 for the first time in its history.
Despite the excitement, a closely watched valuation metric is now flashing a warning that legendary investor Warren Buffett once described as “playing with fire.”
The metric, known as the “Buffett indicator,” compares the total value of the U.S. stock market to the country’s gross domestic product, offering a broad measure of whether equities are overvalued.
The Buffett indicator has now reached a record high of more than 235%, meaning stocks are worth significantly more than the entire output of the U.S. economy.
Buffett, writing in a Fortune article, once warned that levels above 200% are equivalent to “playing with fire,” and history suggests that warning deserves serious attention.
The last time the indicator surpassed 200% was November 2021, after which the S&P 500 declined more than 15% over the following 12 months.
A more severe example occurred during the dot-com bubble, when the Buffett indicator reached a then-record high of more than 147% in March 2000, and the S&P 500 subsequently dropped 42% through the end of 2002.
Buffett, who has led Berkshire Hathaway (BRK.A, BRK.B) for 60 years, built a compounded annual return of nearly 20% over that period, compared to roughly 10% for the S&P 500 index.
Known as the “Oracle of Omaha,” Buffett has long avoided chasing market trends, preferring instead to buy quality companies at reasonable prices and hold them for the long term.
His approach, which includes bargain hunting when other investors are selling, stands in sharp contrast to the momentum-driven buying that has characterized the recent AI-fueled rally.
Analysts warn that today’s record Buffett indicator reading does not necessarily signal an immediate crash, but it does counsel caution about buying overvalued stocks regardless of their popularity.
The recommended strategy, consistent with Buffett’s own philosophy, is to focus on reasonably priced or undervalued stocks across any market environment and maintain a long-term investment horizon.
