In this paper, a new mechanism is proposed to apportion expected reserve costs between electricitymarket agents in the power system. The uncertainties of generation units, transmission lines, wind powergeneration and electrical loads are considered in this model. Hence, a Stochastic Unit Commitment (SUC)is used to apply the uncertainty of stochastic variables in the simultaneous energy and reserve market-clearing problem. Moreover, electrical customers can participate in the electricity market based on theirdesired strategies. In this paper, a novel method is proposed to allocate reserve costs between GenCos,TransCos, electrical customers and wind farm owners. Consequently, market agents are responsible forpaying a portion of the allocated expected reserve costs based on the economic metrics that are definedfor the first time in this paper. Finally, two cases including a 3-bus test system and IEEE-RTS are utilizedto illustrate the performance of the proposed mechanism to share the expected reserve costs.