The tightening of the bands is often used by traders as an early indication that overall volatility may be about to increase and that a trader may want to wait for a sharp price move.

紧凑的布林线被交易员认为是整体波动增加将会出现价格剧烈变动的早期信号。

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By late fall, the SFO and Justice Department both had their eyes on Mr. Hayes, a trader known by colleagues as "Rain Man" for his sharp mind but socially awkward demeanor.

WSJ: U.S. and U.K. in Tussle Over Trader