A daylong campaign by the nation's biggest banks to defy the Federal Reserve and hold the line on interest rates came to an end late Thursday when Bank of America ( BAC) said it would drop its prime rate to 4%. The nation's third-largest bank became the first lender to reduce its prime rate from 4.25% in the wake of the Fed's quarter-point cut. The Charlotte, N.C.-based bank took the action shortly after the close of the trading day. Moments later, Chicago-based Bank One ( ONE) took a similar action. Others are expected to quickly follow suit.