David Rosenberg indicates that the U.S. stock market is increasingly resembling a bubble, with valuations, leverage, and investors' positions at extreme levels never seen in the 40 years since its inception.

Rosenberg is the founder of Rosenberg Research and Associates, which are headquartered in Toronto. He believes that the current bull market's dependence on the progress of artificial intelligence (AI) is much higher than the stock market's dependence on the tech industry on the eve of the internet bubble. He stated that he has been buying U.S. Treasury bonds and overseas stocks in his portfolio, calling the United States a "tech boom center" for which investors are paying an excessively high price.

"I have been in the industry for 40 years, and I can't remember having seen such a high degree of polarization, extreme phenomena, and imbalance as we have today, not only in the market but also in the economic sphere," he said at the Grant's Annual Fall Conference held in New York. "If you don't want me to call it a bubble, then I won't. But what I am seeing now is indeed something I have never seen before."

Rosenberg is known for his neutral stance. He once served as the Chief Economist for Merrill Lynch North America and gained fame for issuing warnings about the U.S. housing bubble before the financial crisis in 2008. Subsequently, he worked at Gluskin Sheff for over a decade before leaving to found his own research company.

In addition to warning about the further increase in dependence on AI for market gains, Rosenberg also pointed out vulnerabilities in the fundamentals of the U.S. economy. He specifically noted that consumers are becoming increasingly reliant on further rises in the stock market to finance their lifestyle.

“I’m really worried about the social impact of the next bear market,” said Rosenberg. He pointed out that those who retire early and rely on their investment portfolios to support themselves will face difficult choices. “What will these people do? Will they go to Walmart to look for a job as a cashier, only to find that even that job has been replaced by robots?”