The wave of so-called strategic alliances between Fannie Mae, Freddie Mac and lenders that quickly swept over the mortgage market in 2000 has had a profound impact on the concentration of government-sponsored enterprise business coming from major lenders. According to a new Inside Mortgage Finance analysis of just released Home Mortgage Disclosure Act data, the share of GSE mortgage purchases derived from just their top 10 customers jumped from 50 percent to 62 percent last