Alibaba may want to block the deal or believes it can exercise a clause allowing it to buy back its stake from Yahoo and seek independence <a href="http://finance.yahoo.com/tech-ticker/article/7899/Yahoo-Alibaba:-The-Good,-The-Bad,-The-Unknown" target="_blank">http://finance.yahoo.com/tech-ticker/article/7899/Yahoo-Alibaba:-The-Good,-The-Bad,-The-Unknown</a>