This article studies mergers in markets where firms invest in a portfolio of research projects of different profitability and social value. The investment of a firm in one project imposes both a negative business-stealing and a positive business-giving externality on the rival firms. We show...

We study a search market where firms may design products of inferior quality to promote them to naive consumers who misjudge product characteristics. We derive an equilibrium in which superior and inferior quality co‐exist and show that as search frictions vanish, the share of superior goods...