We investigate the impact of scheduled macroeconomic news announcements on the U.S. Treasury market’s efficiency. Using intraday data and controlling for microstructure noise, we employ a robust method to construct market inefficiency measures. We find that the U.S. Treasury market is less efficient in the five-minute interval before news arrival. Our findings are robust for different sample periods, macroeconomic news announcements, and market inefficiency measures. We find that investor heterogeneity provides a possible explanation for the decreased market efficiency before scheduled news announcements.