Ally Financial Inc. ALLY

The business

Ally is what became of General Motors' finance arm. It lends against cars, through the dealer, which is a business it has been in since 1919 under one name or another and understands better than any bank. Roughly a third of American new vehicle purchases pass a lender's desk, and Ally sees more of those applications than almost anyone: 4.6 million in the June quarter to produce $13.3B of originations.

It funds that with a purely online deposit base of $154.0B, 92% of it federally insured, gathered by paying savers more than a branch bank does. No branches, no tellers, a rate advertised on the internet.