A slumping mortgage market and upcoming political scrutiny could eat into GSE earnings during the upcoming months, according to one industry expert, but Fannie Mae’s and Freddie Mac’s stock could still outperform the rest of the market by 45 to 50 percent. “Although the GSEs have left the ‘sweet spot’ in the mortgage cycle, namely the refi boom, and Fannie Mae’s [earnings per share] growth is likely to be below trend at 4 percent