Export responses to unanticipated price shocks can be a key contributing factor to the rapid mean reversion of electricity prices, a phenomenon often seen in electricity markets. In this paper, we use event analysis to demonstrate how hourly export transactions respond to negative supply shocks in the Ontario electricity market. Although event analysis has been used for many years in other applications, particularly finance, to our knowledge this is the first time that this technique has been applied to price response analysis in the electricity market. The analysis clearly demonstrates the sensitivity of export volume to price changes, and more generally. the responses of prices and quantities to an unexpected supply shock.