The CBOE Put/Call has been the best this year at identifying tops. As the chart below shows the 10 day moving average pierced the 0.8 level on three occasions. All three occasions led to moves of at least 50 points lower on the S&P 500. There were no false signals.
While it may appear that we are not yet close to a sell signal that is not the case. A low reading today would get us one as we are dropping a very high number.