Abstract The aim of this article is to empirically measure the contribution of the futures market to the price discovery process in the spot market for benchmark crude oils, specifically that for West Texas Intermediate (WTI). For this purpose, we test the hypothesis that the recent evolution of the financial markets has affected the future oil market so as to increase its contribution to the price discovery process of the spot market. We modeled the relation between WTI spot and future prices as a cointegration relation. By using the Kalman filter technique, it was possible to obtain a time-varying measure of the contribution of future markets to the price discovery mechanism. The results show that in the case of WTI, the contribution of the futures market has been increasing, especially between 2003 and 2008 and then again after the start of 2009, evidencing the growing importance of factors particular to the financial markets in determining oil prices in recent years. During 2009, the spot prices adjusted to agents' future expectations rather than to the current supply and demand conditions.