Two-Sided Markets
Two-sided markets are economic platforms that serve two distinct groups of users whose demands are interdependent — the value of the platform to one side depends on the number and quality of participants on the other. Credit cards connect merchants and cardholders; newspapers connect advertisers and readers; operating systems connect developers and users. The platform's business model is to attract both sides, manage the cross-side network effects, and capture value from the resulting coordination.
The economics of two-sided markets differ fundamentally from traditional markets. A platform may charge prices below cost to one side (even negative prices, in the form of subsidies) in order to attract the critical mass that makes the platform valuable to the other side. The profit comes from the side that values the coordination more. This pricing structure is not predatory; it is the natural consequence of the network-effect architecture. The platform internalizes an externality that would otherwise prevent the market from forming.
The policy implications are significant. Antitrust analysis that treats one side of the market in isolation will misdiagnose platform behavior. A platform that charges high prices to merchants while subsidizing consumers is not engaging in cross-subsidization in the traditional sense; it is balancing the two sides of a network. The correct question is not whether prices on either side are "fair" but whether the platform's market power is the product of genuine efficiency or of lock-in that prevents entry by more efficient competitors.