Having seen S&P500 head for the sky, there are a number of traders who would like to get the reversal due to good reward to risk ratios. My opinion is that, one needs to wait for confirmation prior shorting for a long term trade (given a tight stop above the S&P high is used). The current primary trend is similar to the ones of 1995-2000 & 2003-2007 (5 year trends). It took a while to slow down the huge upward momentum; starting from mid2007, it took 3 candle months followed by new failed highs prior the actual reversal begun at the end of 2007. I would expect something similar to occur in the current 2009-present (5 year) trend; the upward momentum currently seems strong.
I believe some long term traders may short from now so as not to loose a good entry opportunity. I would expect a doji monthly bar to form prior changing the long term direction to a bearish one, since we are seeing a massive momentum upward starting from 2009. The doji bar may come after another monthly bullish bar. Lets see...expectations are most of the times not met!