A rally typically ends when the consensus has embraced it and there are few left to buy. It is hard to argue that this rally has been fully embraced as skepticism and confusion seem to be the over riding sentiment. However, in the past two days we have seen a larger move to the bull camp. The Rydex bears have finally started throwing in the towel but we are far from a bullish extreme.
At the same time the market is very overbought and will possibly be maximum overbought at the end of the day. As a result a pullback would not be very surprising.
If we do get a rally today accompanied by heavy call buying I would likely take a short position. Even so I would probably do so by selling naked calls rather than outright shorting as the setup is not great.