Increasingly sophisticated tracking technology offers publishers the ability to offer targeted advertisements to advertisers. Such targeting enhances advertising efficiency by improving the match quality between advertisers and users, but also thins the market of interested advertisers. Using...

Since 2008, multiple smartphone platforms have launched versions of “app stores”, marketplaces where consumers can purchase and download software applications for their smartphone. This paper provides evidence for both demand and supply of “apps” using data on the size and composition of...