As head fake moves go..

The stronger the move and the more obvious the support or resistance level that is taken out, the more effective a head fake move is in creating reversal momentum.

 The range from the last 2 days in the SPY is clear, everyone knows where support is, the earlier break below wasn't a very effective move, it didn't pull any volume, this last move below support did what a head fake move should do, it pulled volume, some would have been stops, but more would be limit orders or plain old short orders (limit or otherwise). This is the point of a head fake move, to trap traders and the more volume the better.

SPY 1 min since. I still would liked to have seen a bigger volume surge on a 1 min bar on the first break below the trendline.