We study the implications of Bitcoin‘s security model for its market valuation. We identify mining shocks by exploiting exogenous variation in mining intensity using a narrative approach in a structural Vector Autoregression. While their impact on transaction speed is short-lived, mining shocks persistently affect trading volumes and market valuations, explaining up to 15 percent of Bitcoin‘s substantial price variation. Our findings can be rationalized in a theoretical framework where mining shocks affect the likelihood to withstand potential attacks and as such impact investor beliefs about the future state of the network and thus Bitcoin’s usefulness as a means of payment.