This conflict was the biggest single factor behind the recent exchange of asset management for brokers by Citigroup and Legg Mason, and it also lay behind an unsuccessful attempt by Morgan Stanley earlier this year to purchase BlackRock.

ECONOMIST: Merrill Lynch

Mr Mack has already noted Citigroup's recent swap of its asset-management arm for Legg Mason's brokerage operation.

ECONOMIST: Morgan Stanley

Despite shedding its insurance underwriting and asset management units in the last year or so, Citigroup continues to operate in a stunning variety of businesses, from subprime mortgage lending and branch banking to investment banking, private equity and securities servicing.

FORBES: Weill Springs To Citi's Defense