Entry by rival app stores on the two currently available mobile operating systems is an exciting potential benefit of the European Union's Digital Markets Act (DMA). Apple and Google will need to share the technical specifications of their interfaces with developers and offer them the same...

This paper studies how a retailer decides the length of product line in a vertically related industry. We study a market with two product varieties. Each retailer decides the number of varieties it procures from an upstream manufacturer. The manufacturer may open an online store and encroach on...