NEGATIVE INTRA‐GROUP EXTERNALITIES IN TWO‐SIDED MARKETS*
研究在已有免费平台存在时，新平台能否通过收费和补贴吸引用户并盈利，发现当组内负外部性相对于组间正外部性足够强（但不过强）时，新平台可能无法成功。
Two types of agents interact on a pre‐existing free platform. Agents value positively the presence of agents of the other type but may value negatively the presence of agents of their own type. We ask whether a new platform can find fees and subsidies so as to divert agents from the existing platform and make a profit. We show that this might be impossible if intra‐group negative externalities are sufficiently (but not too) strong with respect to positive inter‐group externalities.