摩根大通警告：标普500指数将暴跌20%，年底收于4,200点。该公司表示，股市目前过于拥挤，可能会在没有警告的情况下崩盘。JP Morgan warns that the S&P 500 could experience a significant 20% decline, settling at 4,200 by year-end. The firm cautions that the current overcrowded stock market poses a risk of sudden cracks without prior notice.