问题如下：
Initially, Fund TMT held active positions in two realestate stocks—one was over-weighted by 1 %, and the other was under-weighted by 1%. Fund TMT traded back to benchmark weights on those two stocks. Then, TMT selected two different stocks that were held at benchmark weights, one automobile stock and one technology stock. TMT over-weighted the automobile stock by 1% and underweighted the technology stock by 1%. What was the effect of TMT’s two trades on its active share? TMT’s active share:
选项：
A.decreased.
B.remained unchanged.
C.increased.
解释：
B is correct.
考点：Active Share and Active Risk
解析：只有当投资组合的主动权重绝对值的总和发生变化时，主动份额才会发生变化。在TMT基金的两笔交易中，初始头寸和新头寸都涉及两只股票，一只减持1%，另一只增持1%，因此主动权重绝对值的总和没有变化，所以主动份额并没有改变。
这道题答案为啥是active share不变？按公式，权重改变的绝对值相加再乘以1/2，此处前后都涉及权重的变化，为啥能抵消？
