I put on a risk reversal in the Sep SP500 on May 20, 2008 with futures at 1421.00. I bought the Sep 1275 puts for 23.00 and sold the Sep 1545 calls for 13.00. My indicator for the short is a combination of two factors. I use a proxy for option volatility. It is a 10 day average of the average true range. It is highly correlated to implied volatility levels. I like to see this at a low level. The other factor is the Emini SP500- Russell Spread. The spread widens during bullish runs. I like to see it at a high level. The trigger is the combination at the same time. The last two signals were on Dec 25, 2007 and Mar 27,2008. When the setup is fired then I wait for a violation of a daily low. The delta on the position is 40. It equals the percentage of a full contract position. If you bought 10 risk reversals then you are synthetically short 4 SP futures contracts. I bought in one futures short already. The next goal would be to buy in the short calls around $1.00. The exit of the entire position would be the reversal of the entry signal. in other words a high implied volatility spike with a low SP500-Russell spread.