Bank of America has issued a warning to investors, advising them to short the S&P 500 index. The bank's analysts suggest that investors should sell any rebounds in the index until the Federal Reserve takes action and the trade tensions between the U.S. and China are de-escalated. This recommendation reflects a broader sentiment on Wall Street, with some analysts indicating a bearish outlook on U.S. equities. The call to 'sell everything' and short stocks underscores concerns about the current economic climate and market conditions.