Future changes in the way large banks account for mortgage risks could slow down growth at Fannie and Freddie as well as create tougher competition for the two biggest players in the secondary mortgage market. “In essence, the way the capital rules were structured through the late 1980s and into the 1990s facilitated the growth of Fannie Mae and Freddie Mac,” said one GSE observer. “Now, depository institutions – the largest of them at