Fannie Mae reported a first-quarter loss of $11.5 billion and then asked for $8.4 billion in government aid. The rescue of Fannie Mae and Freddie Mac could become the most expensive legacy of the meltdown of the housing market. Most of the largest banks have repaid loans they received from the government, but Fannie and Freddie continue to struggle. "Everyone's trying to sweep it under the rug, but there's a very large embedded loss that hasn't been fully realized yet," said Kenneth Rosen of the University of California, Berkeley. "Someone's going to have to write a check, and it's very large."