Wall Street remains concerned about the level of standardization of Fannie Mae and Freddie Mac operations in a single-security environment where investors would be expected to treat them as completely interchangeable. The Structured Finance Industry Group this week reiterated its concern about the Federal Housing Finance Agency’s plan to avoid “complete alignment” of the two government-sponsored enterprises’ operations. In a May 2015 update on the single security, the FHFA said it would carefully assess business decisions that could lead to different prepayment speeds, but that buy-out and removal policies at the two GSEs are essentially the same. That isn’t...