America's biggest banks have suffered unprecedented losses from the ongoing credit crisis, and that's made some investors question whether the big financial conglomerates should be broken up in order to survive.

Break-up advocates, who for months have been clamoring for Citigroup Inc. to be dismantled, got some validation of their viewpoint this past week. Europe's UBS AG - created through the combination of Swiss Bank Corp. and Union Bank of Switzerland in 1997 - on Wednesday laid the groundwork to tear up its business model after another quarter of steep losses.