Mortgage securitization business at Fannie Mae got a little smaller in June, according to the monthly survey from the government-sponsored enterprise, but the rate at which Fannie Mae business contracts is slowing down. Fannie Mae’s gross mortgage portfolio declined at a compound annualized rate of 9.4% in June. Under Dodd-Frank financial reform, both Fannie Mae and Freddie Mac are required to unwind operations, though the speed at which this happens is a variable. For example, the new numbers show that the unwind is slowing down. Fannie Mae said its gross mortgage portfolio fell at a much-faster compound annualized rate of 15.2% in February, while the government-sponsored enterprise’s entire book of business fell 0.7%. Fannie Mae’s total book of business lessened at a compound annualized rate of 1% June. Year-on-year, Fannie Mae mortgage-backed securities portfolio declined by a little more than $50 million to $231 million, compared to $282 million in June 2010. Fannie Mae mortgage servicers completed 17,246 loan modifications in June, for a total of 101,379 loan modifications in the six months ended June 30, 2011. Write to Jacob Gaffney. Follow him on Twitter @jacobgaffney.