Séminaire Microéconomie : Tous les mercredis
Heure : 12h15 – 13h30
Date : 20/05/2026
Salle : 3001

Roland STRAUSZ (Berlin) – “Oligopolistic Information Markets (with Peter Achim)”

CV : We develop a model of oligopolistic price competition in information markets where buyers purchase and combine signals from multiple sellers. This nonexclusivity transforms competition into “portfolio competition”, with sellers competing against all possible coalitions rather than individual competitors. We fully characterize its pure-strategy competition equilibria and study endogenous entry. In every equilibrium, buyers purchase efficiently from all active sellers. Whether competition protects buyers from rent extraction depends on information complementarities: in duopoly, full extraction occurs if and only if signals are complements; in oligopoly this if-and-only-if condition generalizes to a coalitional “balancedness” condition. With symmetric sellers, balancedness reduces to a geometric test. Entry can paradoxically reduce competitive pressure when entrants provide strong complementarities. Entry is never excessive, contrasting standard oligopoly models where excess results from business-stealing externalities. Instead, efficient entry is always an equilibrium, though insufficient entry equilibria may exist, prompting regulatory intervention.

Organisateurs :

Michele FABI (Télécom Paris – CREST)
​​​​​​​​​​​​Hugo MOLINA (INRIA)
​​​​​​​​​Louis PAPE (Télécom Paris – CREST)

Commanditaires :
CREST