convenience yield

lease rate： 持有现货可以获得的收益，比如我可以把我的牛租出去
storage costs： 持有现货需要付出的储存成本，比如仓库费用
convenience yield：参考文章

By keeping an inventory of the commodity the holder of the commodity can meet unexpected demand without affecting their production process.
Convenience yield refers to the premium associated with holding the product or physical good. It is the implied yield (or return) from simply holding a commodity.
According to Helyette Geman, convenience yield can be “defined as the difference between the positive gain attached to the physical commodity minus the cost of storage.” The convenience yield can be positive or negative. The yield will depend on the commodity, the length of time it is stored, and the level of inventory.

应该就是持有现货带来的隐形便利收益，“奇货可居”的好处具化为一个利率。

计算期货的价格，持有现货需要付出的成本要加上，会得到的收益要减去。

持有现货的收益，就是持有期货的损失，持有现货的损失，就是持有期货的收益