S&P 500 and Japanese Markets See High Momentum Stock Concentration, Near 2000 Tech Bubble Levels

The S&P 500 and Japanese stock markets are experiencing high levels of market concentration, with momentum stocks dominating. Momentum crowding in the S&P 500 has reached levels not seen since the 2000 Tech Bubble, as highlighted by JPM and other sources. The weight of high-momentum stocks in the U.S. markets is at a historic high, and the market cap of top 30 Japanese stocks relative to their index is reminiscent of 2000. Despite these trends, some analysts suggest that the market may not be in a bubble.