A partenreederei is a type of partnership under German and German-influenced maritime law for the joint ownership of a merchant vessel. Each partner, or partenreeder, functions as an equity partner, sharing proportionately in the proceeds, as well as the corporate debt of the business—this liability is not limited. This form of ownership is related to the Dutch partenrederij system that ultimately gave rise to joint-stock companies, and dates back to the Middle Ages.