问题 问答题

假设投资者甲有18 000元现金,并对B股票看跌。该股票不支付红利,目前市价为每股36元。初始保证金比率为50%,维持保证金比率为30%。投资者甲向经纪人借入1 000股并卖掉。
(1)假设该股票跌到24元,投资者甲就可以按此价格买回股票还给经纪人。他做空的投资收益率为多少
(2)假设该股票不跌反升,那么甲就有可能收到追缴保证金通知。到底股价升到什么价位(Y)时,甲才会收到追缴保证金通知呢

答案

参考答案:(1)做空的投资收益为(36 000-24 000)/18 000=66.7%
(2)假设股票价格升到Y元时,甲收到追缴保证金通知。此时,账户上净值为36 000+18 000-1000Y,股票市值为1000Y。此时,下列等式成立;
(36 000+18 000-1000Y)/1000Y=30%
得:Y=41.54元

单项选择题
阅读理解

阅读理解

   As they migrate (迁徙), butterflies and moths choose the winds they want to fly with, and they change

their body positions if they start floating in the wrong direction. This new finding suggests that insects may

employ some of the same methods that birds use for traveling long distances. Scientists have long thought

that insects were simply at the mercy of the wind.

     Fascinating as their skills of flight are, migrating behavior has been difficult to study in insects because

many long distant trips happen thousands of feet above ground. Only recently have scientists developed

technologies that can detect such little creatures at such great heights.

     To their surprise, though, the insects weren't passive travelers in the winds. In autumn, for example,

most light winds blew from the east, but the insects somehow sought out ones that carried them south and

they positioned themselves to navigate directly to their wintering homes.

    Even in the spring, when most winds flowed northward, the insects didn't always go with the flow. If

breezes weren't blowing in the exact direction they wanted to go, the insects changed their body positions

to compensate. Many migrating birds do the same thing.

     The study also found, butterflies and moths actively flew within the air streams that pushed them along. By adding flight speeds to wind speeds, the scientists calculated that butterflies and moths can ravel as fast as 100 kilometers an hour. The findings may have real-world applications. With climate warming, migrating insects are growing in number. Knowing how and when these pests move could help farmers decide when to spray their crops.

1. What's the main idea of the text?

  A. Insects migrate with the seasons.

  B. The wind helps insects greatly in migrating.

  C. Windsurfing insects have real direction.

  D. Scientists have trouble in observing insects.

2. Scientists originally thought that _____________.

  A. insects always waited for their favorable winds

  B. insects chose the winds they wanted to ride

  C. insects were just blown about by the wind

  D. insects positioned themselves in the winds

3. It is not easy to study the migrating behavior of the insects because _____________.

  A. the little creatures can fly very fast      

  B. they have no regular migrating courses

  C. the wind's direction is hard to foresee  

  D. their flight is long and high above ground

4. We can learn form the text that _______________.

  A. insects fly in the way birds do

  B. insects travel more easily in autumn

  C. insects never position themselves when flying low

  D. insects rest a lot when the wind pushes them along