Berkshire Hathaway Inc. is the opening bidder today for a portfolio of Residential Capital LLC's whole loans, a day after ResCap auctioned its mortgage servicing business to Ocwen Financial Corp. for $3 billion, Bloomberg News reported yesterday. Berkshire will start the auction for the loan portfolio, competing against a consortium of financial investors. Yesterday Ocwen beat Nationstar Mortgage Holdings Inc. in an auction that would create at least the fifth-largest U.S. mortgage servicer.