A reaction product comprises a polyester-polycarbonate comprising a polyester unit and a polycarbonate unit, a polycarbonate polymer, and a transesterification catalyst, wherein the polyester-polycarbonate comprises greater than or equal to 75 mole % aromatic ester units, and less than 25 mole % carbonate units. The reaction product has a haze of less than 1.7%, specifically less than 1.0% 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.