股票市场真是看不懂

今天yahoo finance的消息说:"Stock futures jumped Wednesday morning as traders awaited the Federal Reserve's latest monetary policy decision and updated economic projections later in the day."

美联储的货币政策不就是加息吗？前些日子不就是因为这个大跌吗？怎么今天又因此而涨呢？

如果我理解错了，请狠砸。