The literature on early modern commercial cities associates their level of advancement with the degree to which they supply economic actors with crucial information. Seventeenth-century Amsterdam illustrates the point. Its position at the center of the European information flows, the publication of printed price currents and the presence of sophisticated financial institutions such as the Amsterdam exchange and Wisselbank lowered the cost of information and democratized access to it. This, in turn, lowered the information impactedness of market transactions. What resulted was a “modern,” more advanced and efficient market than in the rest of Europe. This article challenges this common narrative. It does so specifically with respect to exchange markets. Based on the accounting books and the commercial correspondence of the Antwerp banker La Bistrate, it reconstructs how exchange markets functioned. Three findings standout. Firstly, postal services set the rhythm for exchange activities. Dealings began on specific weekdays when the mail arrived and ended when it left. Since operators established the rates based on the quotations of the corresponding financial centers, every interruption of postal services resulted in a suspension of the exchange activity. Secondly, this price formation process was not characterized by information asymmetries or driven by opportunistic behavior. The quotations, which arrived by mail, were publicly accessible and thus common knowledge. Thirdly, strategic advantages were not so much associated to location (Amsterdam, London, Antwerp or elsewhere). They were instead largely determined by the quality and scale of the network that individual traders managed to sustain. Traders estimated the opportunities and risks of their exchange dealings based on their correspondents’ assessment of the political and economic development in other centers. It is in relation to these correspondents that information asymmetries and the associated risk of opportunism had to be dealt with.