长期形态二、双重顶和双重底结构

双重顶：双重顶有两个类似高度的高点和对前一次低点的突破。双重顶并不是交易的可靠依据，因为双重顶和三重顶的类似性并且交易范围有限。
突破后的做空目标应该为峰高和底部之间的距离。
 
成交量确认：第二轮波峰处的成交量减少，在突破支撑位后成交量增加。
交易信号：在突破支撑位后做空，并在上一波峰处的价位设置止损。价格通常会反弹到支撑位，而这时支撑位变成阻力位。在价格走势在该阻力位向下反弹时做空，并在支撑位上方设置止损。

双重底

同样，双重底结构也不是交易的可靠依据，因为其类似于三重底结构和交易范围。
当价格突破阻力位时，做多目标为双底和顶部之间的垂直距离。
 
成交量确认：在价格回调时成交量减少，在触及支撑位后成交量迅速增加。
交易信号：在价格越过阻力位后做多，并在上一轮的低点处设置止损。价格之后会反弹，阻力位也相应的变为支撑位。当价格越过支撑位后做多，并在该支撑位设置止损。

Double Tops and Double Bottoms
Double Tops
Double tops are identified by two peaks of similar height, followed by a break below the level of the intervening trough. They are treacherous to trade, partly because of their similarity to triple tops and trading ranges.
The target for a breakout move is measured vertically from the highest peak to the support line drawn through the intervening trough. This is then projected downwards from the breakout point.
Volume confirmation
Reduced volume on the second peak followed by increased volume on the break below the support line.
Trading Signals
Go short on a break below the support line.
Place a stop-loss just above the last peak.
Price often rallies back to the support line which then acts as a resistance level. Go short on a reversal signal and place a stop-loss just above the resistance level.
Double Bottom
Double bottoms are also treacherous to trade, in part because of the similarity to triple bottoms and trading ranges.
The target is measured from the lowest trough to the level of the intervening peak. It is then projected up from the break out above the resistance line.
Volume Confirmation
Reduced volume on the second trough followed by increased volume on the break above the resistance line.
Trading Signals
Go long on a break above the resistance line.
Place a stop-loss just below the last trough.
Price often corrects back to the resistance line which then acts as a support level. Go long on a reversal signal and place a stop-loss just below the support level.

本文翻译由兄弟财经提供

文章来源：http://www.incrediblecharts.com/technical/double_tops.php