AbstractThe Carrera de Indias, considered as a set of circuits connecting Hispanic America to world markets, does not appear as a “monopoly” reserved solely for the Spanish merchants of Cadiz, but rather as a complex commercial system, structured into three autonomous segments, each of them dominated by a mercantile corporation, more or less formalized. In the central part, which linked the two shores of the Atlantic, the merchants registered in the Consulado of the Indies of Cadiz (cargadores) obviously dominated the market. However, these were in turn dominated by the merchants from the consulates of Mexico and Lima in the inland trade (comercio de tierra adentro), which linked the great American ports and fairs with the markets of the interior of the continent, and by the foreign merchants of Cadiz, structured into “nations,” in the exchanges that linked the Andalusian port with the rest of Europe and the world. Thus, the beneficiaries of the Spanish colonial trade in the second half of the eighteenth century were neither only cargadores, nor foreign “smugglers” enjoying the weakness of the Spanish empire as the historiography of the Carrera de Indias has traditionally postulated, but those three groups of traders.After highlighting this singular structure of colonial trade in the Spanish Atlantic, we will consider the different institutional and relational factors that could explain it. Obviously, it is because the different groups of actors involved in these exchanges had a specific social, relational, cultural, and institutional capital that they had a comparative advantage over their rivals in certain segments of the Carrera de Indias circuits, and that they were able to obtain the dominant position that we observe.