Ermotti may need to persuade Switzerland's authorities that UBS should keep "the piece de resistance," Credit Suisse's domestic bank, said Porta's Wittmann. During the financial crash of 2008 it was UBS, not Credit Suisse, that took the lion's share of support from the state. One of Ermotti's biggest challenges may be to prevent Credit Suisse's problems contaminating UBS, which will involve hacking back its investment bank and its unwieldy derivatives. Disentangling Credit Suisse's finances, however, is only a part of the problem. "There are clearly parts of Credit Suisse that have had a bad culture.

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