*.stackexchange.com doesn't cover
I outlines why we don't support this in a blog post here:
If we do end up going full SSL, the domains will move to
*.meta.stackexchange.com, which we can secure easily as we add sites. We don't have definite plans on this yet. We will be working on it in 2014 as we investigate the best way to make our sites faster all over the world.
Accessing SE sites via SSL is not supported so far, this is one of the reasons why. The structure of the meta and chat domains doesn't fit to the way certificates are handed out, SE is planning to roll out SSL to all sites at some point, though I'm not exactly sure how they want to solve this specific problem.