Price drift before U.S. macroeconomic news

Abstract

We examine stock index and Treasury futures markets around releases of U.S. macroeconomic announcements from 2003 to 2014. Since 2008 seven out of 18 market-moving announcements show evidence of substantial informed trading before the official release time. Prices begin to move in the "correct" direction about 30 minutes before the release time. The pre-announcement price move accounts on average for about half of the total price adjustment. This pre-announcement price drift has not been documented before. We examine four possible explanations. The evidence points to leakage and proprietary data collection as the most likely causes of the new drift.