Williams %R was introduced by Larry Williams to determine the overbought and oversold levels. It is a momentum indicator that is similar to Stochastic Oscillator. The indicator shows the relationship of the current closing price relative to the range (high – low) of the past N days, usually 14 days.
%R is a banded oscillator that ranges from 0 to -100. A reading from 0 to -20 is considered overbought and a reading from -80 to -100 is considered oversold.
%R= (High_(N days)-Close_Today)/(High_(N days)-Low_(N days) )*100