A unit of Regions Bank has been fined after investing all of a client's portfolio in a hedge fund that channeled money to Bernard L. Madoff Securities, the fund controlled by convicted Ponzi schemer Bernie Madoff. An arbitration panel found that the unit — Morgan Keegan — didn't perform adequate due diligence on the feeder fund, Greenwich Sentry LP. Now the Financial Industry Regulatory Authority is requring Morgan Keegan to repay the entire $200,000 invested by clients Jeffrey and Marisel Lieberman, plus 6 percent annual interest, as well as $50,000 in punitive damages and $14,000 in expert witness fees.