This research examines the semi-strong efficiency of Bitcoin in the Bitstamp and Mt.Gox markets, showing how the digital currency responds to monetary policy and Bitcoin events. On the one hand, we observe that Bitcoin has become more efficient over time in relation to its own events. On the other hand, Bitcoin is not affected by monetary policy news, highlighting the absence of any kind of control on Bitcoin. These findings are relevant for investors and policymakers since Bitcoin is a financial asset without any connection to the measures of central banks.