John Cieslowski, managing director in credit derivatives at Bank One in Chicago, has left the firm. The departure comes in the immediate aftermath of its integration with JPMorgan. The credit and equity derivatives operation of Bank One are both understood to have been disbanded as a result of overlap between the two firms, officials noted. Lester Coyle, a structured credit trader at Bank One, recently joined Commerzbank Securities in New York in a similar role (DW, 7/18).