基差为期货价格与
标的资产现货价格的差距，通常是指最近月期货价减去
现货价的结果。
现货价与期货价有高度的相关性，但基差并非一成不变。
基差交易(basis trade)就是根据对基差变动的预期而进行的买卖。随着期货趋近
到期日，基差一般会逐渐缩窄，最终归于零（见图2）。
参见Backwardation(现货升水，
倒价)和Contango(现货贴水)。
The difference between
futures prices and the corresponding underlying
cash price. Basis is normally quoted as cash price deducted from futures price of the nearest delivery month. There is a high degree of
correlation between cash and futures prices but the basis is not constant. A basis trade exploits the expected movements in basis. Basis is likely to reduce and eventually to shrink to nothing as the futures contract approaches its
expiry date.
See also: Backwardation, Contango
