This paper reports on a longitudinal study into the use of a strategic foresight tool – the Horizon Scan – in the strategy development process of a UK financial institution. Drawing on concepts of performativity, we build on an emerging literature that demonstrates that strategic foresight tools don't just describe the world, or a future state, they also actively create it. In this way, we argue, strategic foresight tools assume agency in of themselves. Through their interactions with strategists, a theory of the future emerges that can be acted on and performed. Our study identifies four ways that a Horizon Scan is performative – through enroling, temporalizing, consolidating, and persuading – and in so doing, we develop the notion of an activation device that shows how strategic foresight tools, conceptualised as such, broadens our understanding of the active and interconnected roles that they perform, and how this in turn shapes the work of strategy-making.