while there are any number of reasons a trading halt can occur, few of them are particularly beneficial to zynga. In this case the most likely candidate is publ

while there are any number of reasons a trading halt can occur, few of them are particularly beneficial to zynga. In this case the most likely candidate is public disclosure requirements by the SEC. It is tricky to announce things uniformly across a multitide of outlets, sometimes a press release will go out early and the company will ask for a halt until they can get the rest out. In this case it looks like marketwatch had the news at 2:48 but zynga's official press release didn't hit until 2:52.