如题

问题如下：

On September 10, a trader opens a long position in 100 December S&P 500 futures contracts. The initial margin requirement is USD 2 million, and CME requires a maintenance margin of USD 1.5 million. Assume that the position is kept open until September 14 and no withdrawals take place. The following table summarizes the daily change in value of the position for that period:

On what dates will additional margin be required?

选项：

A.

September 12, but not September 13

B.

September 13, but not September 12

C.

September 12 and September 13

D.

Neither September 12 nor September 13

解释：