This screen finds stocks whose Bollinger Band width has shrunk to 50% or less of its recent range. Bollinger Bands(20,2), created by John Bollinger, plot a 20-day simple moving average as the middle band and upper and lower bands two standard deviations away, so the bands widen when volatility rises and narrow when it falls. The lower the percentage, the tighter the squeeze. A squeeze shows that volatility has contracted to a low level, and since quiet periods tend to be followed by large moves, traders watch for a breakout from the bands.
