This dissertation examines trade affordances across three different video games and one novel: The Realm Online (1995), World of Warcraft (2004), Counter-Strike: Global Offensive (2012), and Neal Stephenson's Reamde (2011). By trade affordances, I refer to those interfaces which facilitate the transition of digital items from one player to another. While the study of online economies has an established history, the broader social impact of trade affordances remains largely unexplored despite their ubiquity. I align these aforementioned video games with an increasing automation of trade practices within contemporary multi-user online games, as well as the growing relationship between online and offline economies. In order to demonstrate these connections, I provide a summary of early trade practices collected through blogs, playthroughs, developer notes, patches, and other ethnographic sources such as interviews and forum posts. After describing these trade practices, I survey key economic, ethical, political, and social theories relevant to the act of trading and consuming in online spaces. My critique is influenced by autonomist Marxist theory regarding the automation of work and the cycles of struggle central to the relationship between labour and capital. This positions my dissertation in relation to other game studies scholars who have assessed the relationship between play and labour in video games, such as Nick Dyer-Witherford, Alexander Galloway, and McKenzie Wark. I contend that trade in online games is an increasingly capitalized act reflective of conditions of capital outside the games. In order to demonstrate this phenomenon, I provide close readings of the previously mentioned video games and novel, as well as two single-player games that directly critique the relationship between trade, capital, and play.