Many industry experts are advising Fannie Mae and Freddie Mac to expand so-called front-end approaches to credit-risk transfers that have so far relied heavily on structured debt notes and reinsurance contracts arranged long after loans are sold to the two government-sponsored enterprises. In a comment letter filed with the Federal Housing Finance Agency, Redwood Trust suggested that “a more robust front-end CRT program [should] at least match the volume of back-end transactions.” Through the end of September, Fannie and Freddie have issued $35.88 billion of back-end debt notes covering $1.223 trillion of single-family mortgages, according to Inside MBS & ABS, an affiliated newsletter. Redwood is...