NO.PZ2016031201000027
问题如下：
Which of the following factors most likely explains why the spot price of a commodity in short supply can be greater than its forward price?
选项：
A.Opportunity cost
B.Lack of dividends
C.Convenience yield
解释：
C is correct.
The convenience yield is a benefit of holding the asset and generally exists when a commodity is in short supply. The future value of the convenience yield is subtracted from the compounded spot price and reduces the commodity’s forward price relative to it spot price. The opportunity cost is the risk-free rate. In the absence of carry costs, the forward price is the spot price compounded at the risk-free rate and will exceed the spot price. Dividends are benefits that reduce the forward price but the lack of dividends has no effect on the spot price relative to the forward price of a commodity in short supply.
中文解析：
C选项，便利性收益是持有该资产的一种收益，通常存在于一种商品供应不足的情况下。便利收益率的未来价值从复利后的现货价格中减去，从而降低商品的远期价格。
A选项，机会成本是无风险利率。在没有套利成本的情况下，远期价格是无风险利率的现货价格复利，将超过现货价格。
B选项，分红会降低远期价格，但在供不应求的情况下，缺乏股息对现货价格并没有影响。
麻烦老师可以具体解释一下“股息也是会降低远期价格的benefit，但在供不应求的情况下，缺乏股息对现货价格并没有影响。”的意思吗？股息也是会降低远期价格的benefit - 这里有公式表达吗？
