Economic and reliable operation of power system is a critical foundation to support socio-economic development. Along with technical indicators, financial and commercial indices are also equally important to evaluate the performance of power transmission system. This paper proposed and analyzed a set of financial and commercial indices. Outcome of the Power Grid Company of Bangladesh over last three years were analyzed and presented. With the help of these indices, transmission operators can monitor the trends, take required actions, compare with other utility companies, fix new goals and plan for future development. Ultimately which will help to improve the transmission system performance.