This paper investigates the joint impacts of downstream airline market structure, airport ownership structure, concession services, and low-cost carrier (LCC) presence on airport market power and profit margin. Lerner indexes for a sample of 61 major airports around the world were calculated for the period 2008–2014. Then, regression analysis was conducted to identify the determinants of the airport Lerner index. We find that a more concentrated downstream airline market would reduce the profit margin for a public airport but increase the profit margin for a private airport. A higher share of concession service is found to decrease the airport's overall profit margin (accounting for both aeronautical and concession services). Airports with significant LCC presence have a lower profit margin. Finally, the concentration in airline market is found to have a larger negative impact on airport aeronautical price than on the concession price.