On Tuesday, the Obama administration plans to hold a conference to address the question of what to do with the two companies. Clearly, it would be an inexcusable mistake to reconstitute them as private companies in anything close to their prior form. Some people have suggested recasting them as a single new “Fan-Fred agency” that would continue to securitize and guarantee home mortgages. It’s true that Fannie and Freddie played an important role in developing the market for mortgage-backed securities. But they have completed that work, and they should not be preserved in any form. They should be thanked for their successes and gracefully retired.