Williams %RWilliams %R is defined as the highest high in n periods minus the current price, divided by, the highest high minus the lowest low, and multiplied by minus one hundred so as to be a negative percentage. When %R is at a maximum at 0, the stock is closing at a new high, when %R is at a minimum at -100, the stock is closing at new low.
The signals for William %R are to sell when it goes into oversold .i.e. above -20, and falls back through the oversold line. Or to buy when it goes into overbought .i.e. below -80, and falls back through the overbought line.
Alternatively, another bearish signal is when above -20% the %R line, makes two highs the second lower and the first, while the stock price is making a new high. Or similar, when a bullish signal is formed when below -80% the %R line, makes two lows, the second higher than the first, while the stock price is making a new lows.