The vertical lines on this SPY chart mark all FOMC meeting announcement days in since the beginning of 2014. Other than one exception following the December 17th, 2014 FOMC announcement*, the stock market traded lower within a few days to a couple of weeks.

*The rally that followed the December 17th FOMC announcement came on the heels of a 7 session, 5%+ correction in the SPY. Additionally, following the oversold/FOMC induced rally which peaked 7 days later, the SPY fell back sharply to the Dec 17th announcement level within just 5 sessions, quickly erasing that entire post-Fed rally.

FOMC FED market reactions

FOMC market reactions June 17th