A reaction product comprises a polyester-polycarbonate comprising a polyester unit and a polycarbonate unit, and a transesterification catalyst. The reaction product has a haze of less than 5.0%, specifically less than 3.5% as measured at a thickness of 3.2 mm according to ASTM D1003-00. A thermoplastic composition comprising the reaction product and articles formed from therefrom are disclosed. A method of forming the reaction product is also disclosed.