Is the stock market near its top?

A U.S. equity strategist told me the story of a Japanese portfolio manager who sat in his office in July 1987 asking for stock ideas. The strategist’s model was based on a proprietary survey of investor sentiment, though it never really worked. Nonetheless, he read off a list of dozens of stocks. The portfolio manager then asked if he would kindly put in an order for 20,000 shares of each. The Dow Jones Industrial Average peaked at 2722 in late August and crashed 22.6% on Oct. 19.

A friend was a portfolio manager of a massive growth-stock fund in 1999. He told me he bought shares of Yahoo, Cisco, F5 Networks, Infosys and others every day because money flowed into his fund every day. The tech-heavy Nasdaq index peaked on March 10, 2000. As money began to flow out, he had to sell every day. By year’s end, Nasdaq had fallen by more than half.

I met Cathie Wood as she was filing papers for her “disruptive innovation” funds—to “change the way the world works.” Her ARK Innovation exchange-traded fund, ARKK, launched in October 2014 and charges 0.75% management fees. In 2020 it was up 153% as stimulus money flew in, driving more buying. ARKK peaked in February 2021 with $28 billion in assets. Since then, its net asset value is down 70%, even amid a roaring bull market, especially in tech. Morningstar recently calculated that Ms. Wood’s Ark Invest funds have destroyed more than $14 billion in wealth. One of my favorite Wall Street sayings is, “Don’t mistake a bull market for brains.”

In almost every bull run, stock momentum lures in investors at the worst moment, I call them momos, ensuring they get burned when the buying stops. Since 2009, excepting a few brief sell-offs, cash has been trash. That made some sense during the era of zero interest rates. But now with higher inflation and short rates above 5%? Confusing. Maybe investors are already anticipating another Donald Trump antiregulation pro-growth presidency, forgetting that he is married to a growth-killing pro-tariff agenda. Is the bear dead, or does it have a long fuse?

Predicting stock markets is a fool’s errand. My Series 7 test for General Securities Representative Qualification lapsed long ago, so you won’t get investment advice from me. But there are warning signs.

Have we run out of buyers? Sometimes there are triggers that scare them away: oil shocks, viruses, bank failures. But sometimes they simply collapse from exhaustion. More than 40% of households reportedly own stocks—a higher percentage than in 2000. It was 20% in 2010. Some market indicators also point to asset managers being fully invested. Who’s left to buy?

Market breadth is concerning. The 1973 market peak was driven by stretched valuations of the Nifty Fifty, which included IBM, Coca-Cola and GE but also Polaroid and Xerox. Fifty? Now it’s the Magnificent Seven: Alphabet, Amazon, Apple, Meta, Microsoft, Nvidia and Tesla. Seven? Artificial-intelligence hype, way ahead of even the rosiest of realities, drove Nvidia to make up almost a third of the S&P 500’s first half gains. Another quarter came from Amazon, Meta, Microsoft and Eli Lilly. Maybe fat bulls need Mounjaro.

Stock values feel divorced from reality. The so-called Warren Buffett indicator—the ratio between total stock-market value and gross domestic product—was 138% in March 2000. It’s now 196% Certainly not a buy signal. And Bitcoin, my go-to bubblicious bat signal, is down about 20% since March. A dead canary?

“Don’t worry, be happy,” the bulls sing. Inflation is slain, and the Fed will cut rates. But investors won’t like the reason for those cuts. We’re already seeing earnings disasters—Nike, Walgreens, Lululemon, Delta and Wells Fargo. If the economy slows, earnings glitches and stock implosions become contagious. Plus, banks’ exposure to commercial real estate is scary, with buildings being dumped at huge haircuts almost weekly. This is now infecting rental buildings, and there are signs of a private housing glut. Inventory in Denver is up nearly 37%. Sure, markets climb a “wall of worry,” and bull markets tend to last longer than people expect, but sometimes the nightmares are real. Recessions are like honey to bears.

Even writing about the bear is bullish. Bull runs end when everyone is a believer. Still, another favorite saying of mine is, “No one’s ever lost money taking a profit.” Someday, cash will be king again. I prefer to buy stocks when everyone hates them.

Write to kessler@wsj.com.