This chapter argues that we might better understand postmodernism’s ambivalent appropriation of genre models by theorizing it in terms of a logic of quasi- or “as if” belief that cuts across structures of financial and literary market exchange. Taking recent work in economic sociology and the “New Economic Criticism,” as jumping-off points it shows how a deep-rooted kinship between fiction and finance as forms of writing that mediate value in the modern credit economy (in Mary Poovey’s terms) are becoming newly visible today. The shared condition of fictional texts’ and financial and monetary instruments’ successful market circulation is their solicitation of tacit faith or trust in imaginary things. A desire both to exploit and to subvert this condition of “fiduciary exchangeability” shapes the experiments in supernatural narrative form offered by Bret Easton Ellis’s American Psycho (1991) and Lunar Park (2005), Anne Billson’s Suckers (1993), Stephen Marche’s The Hunger of the Wolf (2015), and Jonathan Coe’s The Terrible Privacy of Maxwell Sim (2010). In the work of these writers we see many of the crucial elements of market metafiction in action.