L2 2010 mock morning 25题是不是错了？ occurs, 历史高位, likely, future, produce

wanghaha

commodities that are most like to produce positive "roll yield" are most likely to have:

A few limitations to storage
B prices that are volatile and at historic lows
C prices that are volatile and at historic highs

我理解应当选择C，roll yield的出现，是future价格今后一路走低，在backwardation的情况下才会出现，
因此如果当前价格处在历史高位，则今后价格会走低。
而答案选B，解释是这样的：
positive "roll yield" occurs when the future price is above the "full carry" price, referred to as backwardation
(这个定义是不是本身就错了？！）, which may occur when prices are low and volatile and producers are concerned that
they will fall further, to a level that is unprofitable. Producers will accept less that the "full carry" price in order to
hedge price risk.

wanghaha

受教了！感谢高手