We obtain data on every mobile app published on the iOS App Store and Google Play Store by the end of 2017 from Apptopia.com. Apptopia specializes in mobile app analytics and serves many of the largest companies in the world. Until 2017, Apptopia has data coverage on over 3 million mobile apps on the iOS App Store and 5 million mobile apps on the Google Play Store. In addition to the basic mobile app information, Apptopia offers mobile app performance estimates by collaborating with mobile app developers and gathering real data on app performance directly from these collaborators’ app developer accounts, including app downloads, revenue, daily average users, and so on. To identify all the app developers who are either public firms themselves or the subsidiaries of public firms on the iOS App Store and Google Play Store, we first retrieve a list of public firms listed on AMEX, NASDAQ, and NYSE with ordinary common shares between 2007 and 2017 from Compustat. By comparing website URLs and firm names between Apptopia and Compustat, we identify 1,382 public firms with over twentytwo thousand apps on the two app stores. Because not all apps on Apptopia have app performance estimates and Apptopia started providing the app performance estimates from July 1, 2014, 318 firms are dropped from our sample. To reduce noises, firms in our sample are limited to those with at least one year of daily app performance data on a continuous basis. Therefore, our initial sample consists of 539 public firms with 2,656 mobile apps. To construct the firm-month panel data set, we collect financial-market and financialstatement data from CRSP and Compustat, respectively. 213 firms are excluded due to missing data. Our final sample has 326 public firms with 7805 monthly observations from July 2015 to December 2017.