In power system studies, congestion in transmission lines and utilization of Flexible Alternating Current Transmission System (FACTS) devices are closely associated and it is very important due to their role in power delivery system enhancement. It is to be noted that the generation companies can exercise their market power which depends on the line flows and the line constraints, generators' location and its share to the individual loads. This issue cannot be overlooked as it creates monopoliness which is a threat to the deregulated market policy. The objective of this paper is to show how the generation companies' market power gets enhanced due the FACTS devices. FACTS devices like Thyristor Controlled Switching Capacitor (TCSC) and Thyristor Controlled Phase Angle Regulator (TCPAR) are taken and used under steady state operation. The market power is determined using Nodal Must Run Share (NMRS) index for the standard IEEE 14-bus system with and without the above FACTS devices and the results obtained are compared. All the above simulations are carried out in MATLAB 7.9-R2009b environment. © 2012 IEEE.