According to CoinMeta, as of August 7th, the Shiller P/E ratio of the S&P 500 index rose to 42.39, exceeding the long-term average of 17.40 and only falling short of the historical peak of 44.19 during the internet bubble period. It also surpassed the valuation level of 32.56 before the 1929 market crash, entering the second time in history that the P/E ratio has exceeded 40. The Shiller P/E ratio is used to measure long-term investment return expectations, and the historical instances of a P/E ratio over 40 currently concentrate during the internet bubble period from 1999 to 2000. With such high valuations, the room for error in long-term valuations of U.S. stocks has decreased, and future returns will depend on corporate earnings growth. If the profitability of artificial intelligence does not meet expectations or if real interest rates rise, the high-valuation environment could amplify market adjustment pressures, putting the expected yield of U.S. stocks at risk of decline over the next decade.