dga

Cramer's Four Horsemen Back in the Saddle

The charts are called Bollinger Bands.

If you have access to Reuters research reports (for example, in
the Charts section of ETrade), they appear in those reports along
with the following explanation:

Technical analysts believe a narrowing of the bands suggests a significant price movement, up or down, will soon occur. Also, many say stocks that move outside the bands and then back inside will soon move toward the opposite band.