China's mainland stock market has lost approximately $2.4 trillion in market value since May, as investors increasingly doubt the profitability of Beijing's AI boom. The CSI 300 index, comprising China's 300 largest listed companies, entered a bear market on October 22, marking a drop of at least 20% from its peak. AI companies now constitute 42% of the market value of Chinese shares listed on the mainland and in Hong Kong, and 57% of trading, according to Goldman Sachs. The Shanghai STAR 50 index, tracking 50 large tech and chip companies, fell 40% in less than four months, erasing about $480 billion. It currently trades at roughly 100 times earnings, significantly higher than the Nasdaq 100's 30 times, despite falling from a peak of nearly 250 times. Analysts attribute the market downturn to weak Chinese consumer spending and skepticism regarding AI companies' ability to generate returns on their investments. Fund manager Dong Baozhen stated, "The stock market later evolved into a speculative crazy bull, and now we see the bubble bursting."