Stocks Advancing Amid Heavy Short Interest - Freddie Mac, Ambac Financial Group Inc (FRE; FNM)

Fannie is up another 14% in pre-market trade, Freddie is up 4.7%. From Schaeffer's Research:

As explained in our education section, short interest is a useful sentiment indicator that measures the level of investor pessimism toward a stock. While it isn't always a simple "long only" indicator, it can give you insight into situations where you might see concentrated buying demand. The purpose of this post is to highlight heavily-shorted stocks that could be in the midst of a potential short covering rally. More details about the methodology are listed below....MORE