Template-Type: ReDIF-Paper 1.0 Series: Tinbergen Institute Discussion Papers Creation-Date: 2015-07-06 Number: 15-080/II Author-Name: Yuyu Zeng Author-Workplace-Name: VU University Amsterdam, the Netherlands Author-Name: Harold Houba Author-Workplace-Name: VU University Amsterdam, the Netherlands Author-Name: Gerard van der Laan Author-Workplace-Name: VU University Amsterdam, the Netherlands Title: Note on ‘Competition in Two-sided Markets’ Abstract: We extend the models in ("Competition in two-sided markets" of Armstrong (2006, Rand Journal of Economics) by adding within-group externalities. In the monopoly and duopoly cases, positive within-group externalities reduce the price of the own group. Negative externalities have an opposite price effect. In the case of a competitive bottleneck, we show by examples that within a certain range of parameter values, a novel phenomenon arises that the platform attracts more agents from one of the groups compared with the social optimum. Classification-JEL: D4, L4 Keywords: Competition economics, two-sided market File-Url: https://papers.tinbergen.nl/15080.pdf File-Format: application/pdf File-Size: 337965 bytes Handle: RePEc:tin:wpaper:20150080