This article examines the role of merchant companies in structuring overseas trade in early modern Europe by considering the commerce of the Merchant Adventurers of England, the ‘regulated’ Company which monopolized the cloth export trade to Germany and the Netherlands in the sixteenth and seventeenth centuries. It examines the Company's trade to its German ‘mart’ town of Stade at the close of the sixteenth century through a detailed case study of the trade of one particular merchant, John Quarles. Using correspondence between Quarles and his factors overseas, it considers how membership of this regulated trading company impacted on the practice of its members, both through its formal regulatory regime and the informal pressures that came with corporate affiliation. However, corporate privileges also created ‘shadow economies’ inhabited by the excluded, those castigated by companies as ‘interlopers’. The article considers the connections between interlopers and those ‘disorderly brethren’ of the company who were prepared to violate corporate regulations in pursuit of opportunities. It shows how the regulatory regimes of merchant companies were shaped by the changing practices of members and non‐members as they responded to the structural changes facing European trade in the early modern period.