Summary Market power assessment is an important aspect of electricity market analysis and operation. This paper aims to analyze the impact of generation technologies and their ownership structure on the potential of market power in a short‐term period. The technological features of hydro and thermal power plants, such as upper and lower production limits, as well as ramp up and down rates are considered. Additionally, wind production uncertainty is modeled with considering spatiotemporal correlation among diverse wind farms. To evaluate the potential of the market power, 2 market concentration boundary problems are solved. These 2 problems seek to find minimum and maximum values of a market concentration measure, while considering operational constraints of a day‐ahead market clearing problem. The results through an IEEE 24‐bus Reliability Test System demonstrate that both boundaries of market concentration move down by greater number of generation owners. Additionally, the upper boundary of the market concentration can be reduced by a more diversified ownership of wind power capacity.