I looked at the Rydex Inverse Dynamic S&P 500, which seeks returns that are inversely 200% of the daily S&P 500 index. The S&P 500 was up 14% in ’06; the Rydex Inverse was down 18%; 1.3X, not 2X.
They may try to get you 200% inverse, but their ’06 performance was not very encouraging.