U.S. prosecutors said that former Bank of America Corp. executive Phillip D. Murphy pleaded guilty to conspiring to defraud bond investors and the U.S. government through a bid-rigging scheme, Bloomberg News reported yesterday. Murphy, former head of the bank’s municipal derivatives desk, admitted in federal court in Charlotte, N.C., to manipulating the bidding process for investment agreements covering municipal-bond proceeds, Steven Tugander, a U.S. Justice Department lawyer, said yesterday. Murphy’s guilty plea resulted from the government’s multiyear probe of bid-rigging of investment contracts involving monies generated by municipal bonds. Bank of America, JPMorgan Chase & Co., UBS AG, Wells Fargo & Co. and General Electric Co. have acknowledged that former employees engaged in illegal activity in connection with the scheme, and the companies paid a total of $743 million in restitution and penalties.