Introduced by Roger Altman in the February 1993 issue of Technical Analysis of Stocks & Commodities magazine, the Relative Momentum Index is a variation of the Relative Strength Index (RSI). Instead of counting up and down days from close to close like the RSI, the Relative Momentum Index counts up and down days from the close relative to a close n-days ago (where n is not limited to 1 as required by the RSI).
As with all overbought/oversold indicators, the RMI exhibits similar strengths and weaknesses. In strong trending markets the RMI will remain at overbought or oversold levels for an extended period. In non-trending markets the RMI tends to predictably oscillate between an overbought level of 70 to 90 and an oversold level of 10 to 30. When the RSI diverges from the price, the price will eventually correct to the direction of the index.