An economy with monopolistic competition is endowed with an information system that produces a public information signal correlated to uncertain costs of production. Investment in the monopolistic competition sector is determined by consumers' savings under uncertainty. Savings are always lower than their efficient levels in the presented economy. If consumers' preferences exhibit prudence, then an improvement of the underlying information system (in the sense of Blackwell 1953) leads to a decrease of expected savings. The social value of information may be negative in that case from an ex ante point of view. Better information may strengthen the market failure caused by imperfect competition. Without precautionary saving (negative prudence), the social value of information is always positive.