我认为美式期权的价值高是因为给了你在有利时机行权获得巨大收益的权力。后者则只有可能获得权益金的差价收益（因为期间只能对冲平仓）。

比如活期贷款的利息一般比定期贷款高就是因为前者包含了贷款人可以在有利时机终止这份合约而用更低的利率重新贷入相同数量的权利。

美式期货期权比欧式期货期权的价值高，7楼的解释意思是对的。
楼主问的其实就是美式期货期权提前执行的条件嘛：其实跟其他标的期权一样分析啊。

首先，这个问题问的太含糊，是问什么是，还是问为什么，还是问什么时候会，提前执行。提前执行的期权是美式；比欧式的价值高在于可提前性能够体现出波动性，而波动性越高，期权的价值越高；至于为什么要提前执行，那要看持有者本身了，哈哈。

流动性较高，风险较低，当然价格更高咯

这是规定问题，美式期权能提前执行，灵活度更大些，所以期权费会比欧式期权高些。

4# fallenangee h
呵，这位朋友，楼主问的应该是，为什么要提前行使期权，而不是为什么美式期权可以提前行使。

我也想知道这个问题的答案，我猜楼主的意思是美式现货看涨期权不应该被提前执行，为什么美式期货看涨期权要提前执行？（期权期货和其他衍生品 John Hull）

美式期权就是规定成可以提前行权的。另外我记得美式期权的价值和欧式不一样是可以用公式推导的，我翻翻看。。。

我想问的是why it's never optimal to exercise an American call option early，但有时候期货期权提前行权却是最佳的

(Early Exercise of Call and Put Option on Futures) In Chapters 3, 4 and 5 we covered American call options on the spot and explained that in the absence of dividends they will not be exercised early.  They will always sell for at least the lower bound, which is higher than the intrinsic value, and usually more.  Call options on the futures, however, might be exercised early.  If the price of the underlying instrument is extremely high, the call will begin to behave like the underlying instrument.  For an option on a futures, this means that the call will behave like the futures, changing almost dollar-for-dollar with the futures price. For an option on the spot, the call will behave like the spot, changing almost one-for-one with the price of the spot.  Exercise of the futures call will release funds tied up in the call and provide a position in the futures.  Exercise of the call on the spot does not, however, release funds, since the investor has to purchase the spot instrument.