On Dec. 31, Berkshire Hathaway's (BRKA +0.83%)(BRKB +0.95%) CEO of more than half a century, Warren Buffett, called it a career. Even though the Oracle of Omaha is no longer involved in his trillion-dollar company's day-to-day operations or oversees its $343 billion investment portfolio, his leadership lessons have left a legacy for successor, Greg Abel, as well as everyday investors.
While Buffett will fondly be remembered for his annual shareholder meeting candor, his long-term vision, and trouncing the returns of the benchmark S&P 500 (^GSPC -0.69%), it's his unwavering stance on value that really sets him apart.
Warren Buffett retired as Berkshire Hathaway's CEO on Dec. 31, 2025. Image source: The Motley Fool.
Warren Buffett's favorite valuation tool recently made history (not the good kind), bringing his $187 billion warning to Wall Street squarely into focus.
The Buffett indicator is a glaring red flag for Wall Street
Whereas most investors rely on the time-tested price-to-earnings (P/E) ratio to quickly evaluate public companies, Berkshire's now-former billionaire boss preferred the market-cap-to-GDP ratio, which is better known as the Buffett indicator.
This valuation tool, arrived at by dividing the cumulative value of all U.S. stocks by U.S. gross domestic product (GDP), was labeled as "probably the best single measure of where valuations stand at any given moment" by Buffett in a rare 2001 interview with Fortune magazine.
Warren Buffett Indicator hit an all-time high of 239% last week, the most expensive stock market valuation in history 🚨🚨 pic.twitter.com/NoIMxNRGkP
-- Barchart (@Barchart) June 10, 2026
When back-tested to January 1970, the Buffett indicator has averaged approximately 88%. This is to say that the aggregate value of U.S. stocks has averaged 88% of the value of U.S. GDP. On June 1, 2026, the Buffett indicator reached its highest close in history of 238.5%, or roughly 171% above its 55-year average.
Previous instances when the Buffett indicator catapulted higher were all followed by substantial stock market sell-offs.
Image source: Getty Images.
Warren Buffett's warning echoes louder by the day
As a long-term investor, the Oracle of Omaha always spoke highly of the U.S. economy, stock market, and American spirit. But beneath this unwavering long-term optimism, Buffett's actions occasionally disjoined from his words.
In the 13 quarters (Oct. 1, 2022 – Dec. 31, 2025) leading up to his retirement as Berkshire Hathaway's CEO, Buffett was a persistent net seller of equities. Berkshire's consolidated cash flow statements show Buffett sold approximately $187 billion more in stock than he purchased over this period.
While some investors have postulated that he was building a war chest for his protégé, Abel, the likely catalyst behind this selling was Wall Street's otherworldly stock valuations. No matter how much Buffett values a company's competitive edge, management team, and/or capital-return program, he simply isn't sticking around if he doesn't feel he's getting a good deal.
Shiller PE Ratio is now just 3.5% away from passing the Dot Com Bubble as the most expensive stock market valuation in history 🚨🚨🚨 pic.twitter.com/1ceOa3yhfs
-- Barchart (@Barchart) June 1, 2026
Warren Buffett is right to be skeptical. According to the time-tested S&P 500 Shiller P/E Ratio, this is the second-priciest stock market on record (dating back to January 1871), trailing only the months leading up to the bursting of the dot-com bubble.
Every previous occasion in which the Shiller P/E has surpassed 30 was eventually followed by a 20% or greater decline in the Dow Jones Industrial Average (^DJI -0.22%), S&P 500, and/or Nasdaq Composite (^IXIC -1.33%).
Buffett's actions often spoke louder than his words, and his $187 billion warning to Wall Street echoes louder with each passing day.
