问题如下：
Initially, Fund ABC held active positions in two realestate stocks—one was overweight by 1 %, and the other was underweight by 1%. Fund ABC traded back to benchmark weights on those two stocks. Then, ABC selected two different stocks that were held at benchmark weights, one automobile stock and one technology stock. ABC over-weighted the automobile stock by 1% and underweighted the technology stock by 1%. What was the effect of ABC’s two trades on its active risk? ABC’s active risk:
选项：
A.decreased.
B.remained unchanged.
C.increased.
解释：
C is correct.
考点：Active Share and Active Risk
解析：主动风险受股票之间相关性的影响。不同行业的两只股票的相关性低于同一行业两只股票的相关性。因此，新头寸（汽车/科技股）的相关性低于初始头寸(房地产/房地产)的相关性。两只股票的相关性较低，两只股票头寸对主动风险的贡献就越大。
老师，这道题是问的 active risk 包括active share 和 相关系数。active share是一样的 ，所以看相关系数。 后一次投资于不同的行业所以相关系数低一些，而前一次投资于房地产业 比较集中 相关系数高。我们在比较两次的时候应该是要和benchmark比较，但是并不知道benchmark是投资的一些什么呀？如果benchmark是投资不同的行业 更加分散化， 那后一次投资就和benchmark比较像。后一次投资active risk就比较小？
