<p>In most of the industries, state-owned-firms compete with private firms and equilibrium outcomes in these mixed markets may differ compared markets involving only private firms. An important aspect of competition is to collect information about the industry and customers. In this study, we analyze informational equilibrium outcomes when a private firm competes with a social welfare maximizing state-owned-firm in a market. An advantage of cooperation in information sharing and data disclosing is that all firms predict the environment and market changes better, which may increase production efficiency. On the other side, there are competitive disadvantages of sharing information with competitors. In a model where a private and a state-owned enterprise compete in quantities (à la Cournot) and each receives noisy signals on stochastic demand, we analyze firms’ incentives to disclose private data. We establish that information sharing heavily depends on the substitutability of goods. When products are substitutes, neither of the firms shares information with the other one. However, when products are complements, both the state-owned enterprise and the private firm completely disclose information.</p>