Online platforms, such as Google, Facebook, or Amazon, are constantly expanding their activities, while increasing the overlap in their service offering. In this paper, we study the scope and overlap of online platforms' activities, when they are endogenously determined. We model an expansion...

We consider some two dynamic models of entry in mobile telephony, with and without strategic pricing, and taking into account market penetration at entry, locked-in consumers and tariff-mediated network externalities. We show that on/off-net differentials may reduce the possibility of entry if...

We investigate how the expansion of Craigslist into different states over a 11 year period in the United States affected the incidence of HIV. Using a natural experiment setup, we identify the effects of Craigslist's entry on HIV trends by exploiting the variations across states and time. After...

Local telecommunications competition was an important goal of the 1996 Telecommunications Act. We evaluate the consumer welfare effects of entry into residential local telephone service in New York State using household-level data from September 1999 to March 2003. We address the prevalence of...

In this paper, we evaluate the consumer welfare effects of entry into residential local phone service in New York State. Residential local phone service competition was an important goal of the 1996 Telecommunications Act. We provide a detailed evaluation of its effects on consumer welfare using...

Past empirical literature provides strong evidence that competition increases when new firms enter a market. However, rarely have economists been able to examine how competition changes with the threat of entry. This paper uses the evolution of the zip code level market structure of...

In this paper, we study entrepreneurial innovations in an industry characterized by network effects. We show that the presence of network externalities tends to make the entrepreneur prefer sale to entry. Moreover, we also show that the incentive to innovate for entry decreases when network...