In this paper, we derive the dynamics and assess the economic value of currency speculation by formalizing the concept of a trader inaction range. We show that exchange rate returns comprise a time-varying risk-premium and that uncovered interest parity (UIP) holds in a speculative sense. The often-cited ‘forward bias puzzle’ originates from the omission of the risk-premium in standard UIP tests. Consistent with its popularity among market professionals, the carry-trade strategy can be rationalized as it systematically collects risk-premia, however, the economic value generated by bilateral carry-trades is limited.