@java, you can't compare stock index futures with commodity futures... those are completely different. Stock index futures are very much related to their underlying index. They will not differ much during active trading hours from each other. The arb is too easy... the only differentiating factor is dividends. Since the underlying stock stays the same stock, unless dividends are paid before futures expiry. And I wouldn't call index futures a bet on the underlying... it's just the forward price... that relation is nearly fixed.... Commodity futures, their underlying is basically totally different from expiry to expiry. So corn spot has almost nothing to do with corn Dec futures... Since the April corn is different from the Dec corn. Supply/demand will be different between April and December. But also the quality might differ. And because they can be so different, Commodity Futures are more like a bet....