Drugs, Showrooms and Financial Products: Competition and Regulation when Sellers Provide Expert Advice
David Bardey  1@  , Denis Gromb  2, *@  , David Martimort  3, *@  , Jerome Pouyet  3, *@  
1 : University of Los Andes
2 : Groupement de Recherche et d'Etudes en Gestion à HEC  (GREGH)
GROUPE HEC, CNRS : UMR2959
1, avenue de la Libération 78351 JOUY EN JOSAS CEDEX -  France
3 : Paris School of Economics
Université Paris I - Panthéon-Sorbonne
Paris -  France
* : Corresponding author

We consider a market in which sellers can exert an information-gathering effort to advise buyers about which of two goods best fits their needs. Sellers may steer buyers towards the higher margin good. We show that for sellers to collect and reveal information, profits on both goods must be sufficiently close to each other, i.e., lie within an implementability cone, which competition or regulation may ensure. Instruments to do so vary with the context. Controlling market power while improving the quality of advice is more difficult when sellers have private information on the profitability of the goods.


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