Howard Marks, co-chairman and co-founder of Oaktree Capital Management, has cautioned that U.S. stocks appear to be in the early stages of a bubble, with valuations stretched relative to fundamentals. He compared the current market environment to the late 1990s, a period marked by irrational exuberance and overvaluation in technology stocks. Despite this, Marks does not see immediate signs that a market correction is imminent, noting it has been 16 years since the last serious correction. He advised investors to exercise caution after a prolonged bull run by incorporating more defensive strategies into their portfolios. Specifically, Marks recommended shifting investments from equities to credit, which he considers inherently more defensive. This approach aligns with Oaktree's traditional focus on credit markets. Marks emphasized that while the bubble is in its early innings, mean reversion is very likely, suggesting that valuations could adjust over time.