This paper investigates how carry trades altered the efficiency of the Japanese quantitative easing policy between March 1995 and September 2010. Monetary policy shocks are identified by means of a data-driven Structural VAR approach. Accordingly, our results rely exclusively on the statistical properties of the data through non-Gaussian identification. We show that carry trades, by altering the portfolio re-balancing channel, have attenuated the impact of the Japanese quantitative easing policy on growth.