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Williams Percent Range (%R)
%R (Williams Percentage Range) is a momentum indicator that helps to highlight overbought and oversold areas in a non-trending market. As seen from its name, it was developed by Larry Williams.
The Williams %R is interpreted as the Stochastic Oscillator but depicted upside-down. There is no internal smoothing in the Stochastic Oscillator. Readings in the 0 to -20% range show that it is overbought while readings in the range of -80 to -100% demonstrate that the security is oversold. As with all overbought/oversold indicators, before trading it's worth waiting for the security's price to change direction. As the security's price continues to increase or to decrease, it is quite untypical for overbought/oversold indicators to stay in that condition for a long time. Because it can take some time before the price shows signs of deterioration selling on the first indication of an overbought signal may diminish profit.
The ability of the Williams %R indicator to anticipate a reversal in the basic security's price is extremely interesting. Williams %R usually creates a fall and turns upwards a few days before the security's price moves upwards. Also very often, the indicator reaches a high and turns down a few days before the security's price follows suit.
The formula to calculate Williams' %R is:
( Highest High in n periods - Today's Close / Highest High in n periods - Lowest Low in n periods ) * -100