Earlier in June, I had discussed the prevalence of different frequencies in the difference between the Russell 2000 and S&P 500.  One of these frequencies is currently reaching a peak, with Friday putting IWM 0.006 above SPY for daily log-return.  Since May of 2000, the average difference between IWM and SPY has been marginally positive at 0.00027, with a standard deviation of 0.0068. 

    As you can see, as the difference reaches this mean plus one standard deviation, the following days see a trend reversal.  I would consider shorting the Russell 2000 tracker IWM and going long on the S&P 500 tracker SPY to make risk-free profit on this trend.