Looking at this 3 minute chart of the YM contract right around fed time today. What I want to point out is actually the setup that occurred about 30 minutes after the 2:15 info. I like to watch how the market goes into and acts around the 3:00 EST time after the fed. During the announcement I was looking at the bonds and noticing how they showed strength around the number. Yes they pulled down but the follow through was to the long side. SO this was the first signal of overall market sentiment. Then we saw the bulls try to push forward again around 2:45. You can see this on the chart by those green candles, but notice the long wicks showing us rejection. Thats another bearish sign. Then the market consolidates into a perfect triangle pattern. When it breaks with good volume to the downside of the triangle thats a clear signal to look at a smaller time frame and get on a pullback. So basically you get three signs confirming the move. At that point you go with it.
Notice also that the lines drawn on the chart had been drawn before the open. They are key levels from the overnight session. See how well they where respected on the move down. These would be great targets to take some profits on the move as it progressed down. 
