Article dans une revue: We develop a theoretical framework to analyze the choice between secrecy, patent and open access. We consider a firm that can use a basic innovation to develop an application. The basic innovation can also lead another firm to develop a different application. We determine the incentives for the basic innovator to give open access to the basic innovation or to keep it secret. We show that open access emerges more often if the company that owns the basic innovation has the option to protect it by a patent.