Whether the bollies are tightening or opening up will depend on which chart/time interval you are looking at. Bollies just represent a price range the stock is expected to trade in with an 80% probability based on a mathematical formula which looks at the past range of prices. In a way, it measures volatility. As the price stabilizes, the bollies will tighten. They also consider price trend, so you'll see them sloping up or down accoridingly. Based on experience, any stock that is actively traded doesn't like a stagnant price: no one can make money off of it, so when the bollies tighten due to a stable price range, it usually means a move is coming. If they open up, it's usually because the price is moving, or trying to move. I could say more, but there are other better sources you can check out if you want more. Hope this helps.
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