During the May 4 Fed Day, the FOMC announced a 50bps increase to the reserve rate.
A purely technical reaction drove stocks higher on Wednesday, as is common with nearly highly-anticipated market event, including FOMC days. Volatility is built up in advance of the event and sells off afterwards, which also causes a rise in equities as Market Markets adjust their books.
However, the equity rally and falling volatility are short-term market adjustments that do not result in sustainable rallies. Investors are merely taking an opportunity to reduce their long exposure in a structural bear market.