In a further sign of recovery in the thrift sector, Dime Bancorp's long-term and senior debt was upgraded last week to one notch below investment grade by Standard & Poor's. "We saw further confirmation of improved operating performance" by the thrift's main subsidiary, said bank ratings analyst Glen Grabelsky. The rating agency raised Dime Bancorp's rating to BB-plus from BB-minus. The ratings outlook for the holding company remains "positive," S&P said. The outlook of its subsidiary, Dime Savings Bank of New York, was upgraded to "positive" from "stable." Standard & Poor's noted that Dime has continued to resolve earlier real estate problems and has realized benefits from mergers and acquisitions.