Joint patenting by companies, the sharing of property rights on inventions, is a relatively unknown phenomenon that is generally seen by patent lawyers and firms alike as a second-best option that, if possible, should be avoided. However, the number of joint patents has increased during the last couple of decades and despite its impopularity firms frequently engage in co-ownership of patents. This exploratory study is one of the first contributions that provides insight into relevant, international, legal complications of joint patenting, sectoral trends and patterns and the motivation of companies to enter into these specific patenting agreements.