In automated exchange system, a single matching unit is supplemented with a calculation unit and a global memory accessible by both the calculation unit and the matching unit. Such a computer architecture will make it possible to perform some of the calculations related to the volume and/or prices of the baits needed in the matching to be performed in advance. The matching process is able to use the values resulting from the pre-calculation when needed, and since no or few calculations are done in one of the most critical parts of the system, i.e. the matching unit, the process of matching combination contracts can be performed at a much higher rate. Hereby the performance of the matching process will be significantly increased. The provision of one or several calculation units will make it possible to perform even very complex calculations can be performed since most calculations need not be performed in real time.