Fannie Mae and Freddie Mac appear to have the most to lose from legislation that would create a so-called Ginnie Mae Choice program, according to a soon-to-be-released financial analysis of the initiative. The analysis suggests that close to 90 percent of the $30 billion in mortgages expected to be generated by the Choice program in a given year would come from the conventional mortgage business currently handled by Fannie Mae and Freddie Mac. The balance,