I was under the impression the majority of the change in stock price for Yahoo(if not all) was related to them owning a large share of Ali Baba stock which has skyrocketed in value. And this purchase was made before Marissa Mayer took over.
This could be the case. I wasn't able to quickly find market cap information for Ali Baba prior to it's US listing. Every since the Ali Baba IPO, Yahoo!'s stock has closely tracked BABA.
