BlackRock and Jean-Pierre Mustier's blank-check firm are among investors expressing interest in Credit Suisse's asset management arm, three sources told Reuters, as the Swiss lender explores options for the unit after a run of costly scandals. U.S. investment firm State Street Corp is also eyeing a rival bid for all or part of the Swiss bank's fund management business, while European asset managers including Germany's DWS are waiting in the wings, the sources said, speaking on condition of anonymity.