S&P; Lowers Debt Rating for Bankers Trust: The rating firm said it is concerned about the company’s involvement in exotic derivative securities. The change affects $5.6 billion of outstanding debt held by Bankers Trust New York Corp. The bank’s senior debt rating was reduced one notch, from AA minus to A plus. The rating is the third-highest that Standard & Poor’s Corp. assigns and signifies that the bank’s bonds still have favorable investment qualities. But it is below the prestigious AA ranking that designates highest quality. The downgrade probably won’t make it more expensive for Bankers Trust to borrow money and shouldn’t hurt the bank’s ability to attract business, analysts said.