First Mariner Bancorp, the holding company for Maryland community bank 1st Mariner, plans to file for chapter 11 protection in order to sell the bank, the Wall Street Journal reported today. The company has an offer that would provide $100 million of new capital from a group of private-equity investors — Priam Capital, Patriot Financial Partners, GCP Capital Partners and TFO Financial Institutions Restructuring Fund LLC — and investors from the Baltimore business community. The offer will be tested at auction. First Mariner said that it would ask the bankruptcy court to approve the auction rules quickly but didn’t say exactly when it plans to file for bankruptcy. First Mariner had become undercapitalized, it said in recent financial disclosures, and wasn’t in compliance with Federal Deposit Insurance Corp. and Federal Reserve Board of Richmond capital requirements.