The risk mapping derived from the various economic activities presented by Thomas Aquinas enables the development of different typologies, which can then be cross-referenced with one another. Risk can be classified according to activity, such as loan, commercial exchange or limit cases of market exchange; according to whether it is a quantitative or qualitative risk; according to whether it is an error in understanding the transaction, a commercial risk imposed by external conditions on the co-contractors, or a strategic risk, which is an internal risk arising from the lack of information on the co-contractor’s intention. They can also be distinguished according to whether the risk relates to the licitness of the activity, the conditions under which it is carried out or a remuneration risk. Finally, a distinction must be made between risks explicitly named by Aquinas, risks implicitly deducible from the situation described and risks induced by Aquinas’s treatment of the situation. This approach reveals a dynamic structure of risk in Aquinas’s thought, with risks emerging both upstream of the operation—concerning the nature of the activity and the nature of the good exchanged—and during the operation itself, involving a range of additional risks.