Bull spread constructed through the purchase of a call with a lower strike price and the simultaneous sale of a call with the same expiry but with a higher strike price 是指投资者卖出一个执行价格较高的看涨期权，同时买入一个执行价格较低的看涨期权，也称为卖权多头价差(交易) 。
2.
Bull spread constructed through the purchase of a put option with a lower strike price and the simultaneous sale of a put option with the same expiration but with a higher strike price 是指投资者卖出一个执行价格较高的看跌期权，同时买入一个执行价格较低的看跌期权，也称为卖权空头价差(交易) 。
