John Bollinger says that a Band Width squeeze has preceded many spectacular moves on the S&P 500. A Bollinger Band squeeze highlights when the bands contract into a narrow “neck” indicating low volatility. The squeeze is normally signaled by a fall in the Band Width indicator to below 2.0%.
Upward breakout from a narrow “squeeze” in late January flagged a strong advance, from 2280 to 2400.
Now we have the opposite, with breakout below 2360 warning of a correction. But Bollinger warns that the market often starts with a fake move, in the wrong direction, before the real move commences. So we need to be cautious.