美股为什么暴跌？这个问题的答案可能涉及到多个方面，下面我们来一一解析。

首先，美股暴跌可能是由于市场风险偏好下降引起的。当全球市场情绪变得悲观时，投资者可能会减少对风险资产如股票的配置，转而投向更安全的资产如债券或其他避险产品。此外，如果全球经济增长放缓或出现衰退，也可能导致投资者对美股的预期发生变化，从而引起暴跌。英文翻译为: Why have US stocks experienced a sharp drop? This question may involve multiple reasons, let's analyze them one by one.

Firstly, the sharp drop in US stocks may be caused by a decrease in market risk appetite. When global market sentiment turns pessimistic, investors may reduce their allocation to risk assets such as stocks and shift to safer assets such as bonds or other hedging products. Additionally, if global economic growth slows down or a recession occurs, it may lead to changes in investors' expectations for US stocks, thereby causing a sharp drop.