We provide a theoretical framework to discuss the relation between firm size and vertical structures. The framework is based on a Hotelling model with three downstream and three upstream firms. Each downstream firm procures its input from each upstream firm and the procurement problems affect...

After the September 11th attacks, passengers avoided air travel. Hence, companies competing with air carriers may have benefited from the terrorist attacks. Using the market model with a dummy variable and generalized autoregressive conditional heteroskedasticity (GARCH) for an event study, we...