Very little is known about Collard de Marke, whose account books I examined in the Municipal Archives of Bruges in the summer of 1937, except that he was one of the sixteen money-changers licensed to practice in Bruges during the 1360's. That much is clear from the municipal records in which he is listed among the money-changers who were fined because they had exchanged nobles (a Flemish coin) at an illegal rate. His account books are of great value to the business historian because they show very definitely that the medieval money-changers did not confine themselves to mere exchange transactions and to trade in gold and silver, but that, as early as the middle of the fourteenth century, they had extended their field of activity by going into the banking business. They received money on deposit and made loans to reliable customers.