Some railroad crossings have gates that block drivers from going through when a train is approaching. Others have flashing lights to alert drivers that a train is coming. They could drive on, but doing so is risky.
The stock market doesn't have the equivalent of a gate that prevents investors from losing money when danger lies ahead. However, I think it does have something similar to a flashing light. His name is Warren Buffett.
Buffett has studied the market for decades and knows when caution is warranted. And he's currently flashing a $344 billion warning that Wall Street (and many investors) are blissfully ignoring.
Image source: The Motley Fool.
Money speaks volumes
To be sure, Buffett isn't appearing on TV prophesying stock market doom and gloom. He hasn't written op-ed pieces in major newspapers advising investors to exercise caution. Such efforts aren't Buffett's style. However, what he is doing -- and not doing -- with Berkshire Hathaway's (BRK.A 0.16%) (BRK.B 0.11%) money speaks volumes.
Buffett has amassed a cash stockpile (including cash, cash equivalents, and short-term investments in U.S. Treasuries) for Berkshire that totaled $344 billion at the end of the second quarter of 2025. The only time the conglomerate has had more cash was in the previous quarter, when its cash position stood at nearly $348 billion.
What Buffett isn't doing with Berkshire's money is buying many stocks. He has been a net seller of stocks for 11 consecutive quarters. The legendary investor hasn't even authorized stock buybacks of Berkshire Hathaway shares since the middle of last year.
Is this a flashing warning for Wall Street and investors? I think so. Buffett appears to be saying (with Berkshire's money) that most stocks are too expensive to buy right now.
Blissfully ignoring the Oracle of Omaha
Wall Street and many investors are indeed blissfully ignoring the Oracle of Omaha. Two factors confirm this.
First, analysts in aggregate seem to have few concerns about overall stock valuations. As a case in point, 405 stocks in the S&P 500 have consensus analyst ratings of buy or better. Only three stocks in the widely followed index have consensus sell ratings.
Second, the S&P 500 is trading at an all-time high. You might even say that many investors are being greedy these days. That brings to mind Buffett's famous statement in his 1987 letter to Berkshire Hathaway shareholders: "We simply attempt to be fearful when others are greedy and to be greedy only when others are fearful."
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Key Data Points
It's also instructive to look back at something Buffett said more than two decades ago. In an article for Fortune magazine in 2001, he discussed the ratio of total U.S. stock market capitalization to gross national product (GNP). This valuation ratio, with gross domestic product (GDP) replacing GNP, is now known as the Buffett indicator. Buffett stated then that when this indicator approaches 200%, investors "are playing with fire."
Where does the Buffett indicator stand today? It's over 213%.
What should investors do?
Maybe investors shouldn't pay attention to Buffett. Perhaps the legendary investor should be buying stocks hand over fist rather than building a huge cash position. He would be the first to admit that he has been wrong in the past.
However, I don't think ignoring Buffett's warning is the best move. Instead, following the multibillionaire's general approach seems to be a prudent course of action, given that stock market valuations are at historically high levels.
Importantly, Buffett isn't panic-selling. Berkshire still owns around $300 billion worth of stocks. This underscores Buffett's underlying focus on the long term, a view that I think all investors should have. He is even buying some stocks (albeit not many) that meet his stringent selection criteria. As we've already seen, Buffett has also built a large cash position that he (or his successor) can put to use when stock valuations are more attractive.
This strategy of focusing on the long term, being highly selective about which stocks to buy, and staying in cash when stock valuations are frothy is one that Buffett has employed for decades, by the way. It's an approach that has been enormously successful.
Ignore the legendary investor's warning at your portfolio's potential peril.
