What to make of the Fed?

So Janet Yellen and the rest of the Federal Reserve Board of Governors voting members decided to hold off longer on tightening. Since the announcement came out the S&P 500 has dropped roughly 50 points as of mid-morning today. “Perhaps a little buy the rumor, sell the fact” action.  How much would the market be down if they had raised interest rates 25-basis points to a Fed Funds target of 0.25% to 0.50%? Remember this is what we are discussing.