How the air travel restrictions to India impacted the global airline industry's stock returns? An event study analysis

We examine the impacts of the travel restrictions and bans imposed by several nations on India. Hence, our interest is concerned with the airline stocks listed in the nations' leading stock market, which have imposed restrictions/bans as of 30 April 2021. Initially, we had 20 nations that either imposed travel restrictions or travel bans. Further, the airline stock to be included in the sample must have a history of regular trade, and data for the estimation and event window is available. Owing to these conditions, we include 34 airline stocks across seven nations in our final sample.
We collect the adjusted closing prices, the quarterly revenue, and net earnings of the sample firms from Yahoo Finance. We also collect the closing prices of the leading stock market indices of the sample nations. The adjusted closing prices have been collected for t-216 to t+5. The quarterly revenue and net earnings have been collected for the four quarters of the year 2020.