This paper provides a theory of general equilibrium with externalities and/or monopoly. We assume that the firm's decisions are based on the preferences of shareholders and/or other stakeholders. Under these assumptions a firm will produce fewer negative externalities than the comparable profit...

I examine an environment where advertisers can "seed" word-of-mouth advertising by providing initial information about a product to specific users of a social network. Discussion over a social network generates spillover effects for firms when consumers can use the social network to inform each...