This article argues that the efforts to understand, shape and regulate private security markets and their implications could be greatly enhanced by a better conceptualization of what kind of market the private security market is. While the momentous scholarly literature and practical discussion about private security acknowledges that the commodification of security is contested, it does not fully acknowledge the depth of this contestation or its implications. Security belongs to the "contested commodities" that is to the category of things that some think cannot or should not be commodified. This has far reaching consequences for market practices and hence for the shape the market takes. More specifically as the article shows with reference to the developments in Western Europe and the USA/UK, market practices circumvent the contestation by minimizing its salience and obfuscating the market. The article looks at how they do this in relation to three core nodes of contestation surrounding the state monopoly on legitimate use of force, mercenarism, and the risk for rampant insecurity. It shows how the result is a peculiar form of market spanning the public-private; inside-outside and the safety-threat divides; a "transgressive" market. The article concludes insisting that the direct implication is that security markets are not simply "private". Departing from this insight will provide a clearer point of departure for those trying to understand, shape, or regulate security markets.