Fannie Mae has quietly begun to win back some of the market share it lost last year to Freddie Mac – in spite of significant corporate turmoil, an historic regulatory settlement, tougher regulatory requirements, and continued Congressional pressure. Our Inside Mortgage Finance MBS Database reveals that Fannie issued $229.4 billion of single-family mortgage-backed securities during the first six months of this year. That total, which includes only pass-through pools, represents an 8.8 percent increase from…