[Rosenberg said the U.S. stock market is becoming more and more like a bubble, and the extreme levels of many indicators have not been seen in 40 years of practice] On October 14th, David Rosenberg said that the U.S. stock market is becoming more and more like a bubble, with valuations, leverage, and investor positions all at extreme levels never seen in his 40 years of practice. Rosenberg is the founder of Toronto-based Rosenberg Research & Associates. He believes that the current bull market is much more dependent on the development direction of artificial intelligence (AI) than the stock market was on the technology industry on the eve of the formation of the Internet bubble. He said he has been buying U.S. Treasuries and overseas stocks in his portfolio, calling the U.S. the "center of the tech boom" for which investors are overpaying. In addition to warning the market of further rising reliance on AI, Rosenberg also pointed to vulnerabilities in U.S. economic fundamentals. In particular, he noted that consumers are increasingly reliant on further gains in the stock market to fund their lifestyles.