After their experience with Fannie Mae and Freddie Mac, you'd think that Congress would no longer be interested in creating companies seen by the market as backed by the government. Yet that is exactly what the relevant congressional committees -- the Senate Banking Committee and the House Financial Services Committee -- are now considering.

In the wake of the financial crisis, the idea rapidly gaining strength in Washington is to create a systemic risk regulator. The principal sponsor of the plan is Barney Frank, the chair...