^*University of Augsburg, Institute of Materials Resource Management

We explore the drivers of the WTI and Brent oil price differential in a daily data set between 1995 and 2019 using an ARDL model and structural break testing. We find a major break in the spread time series in December 2010. The key spread determinants are the convenience yield, as a proxy for crude oil inventories, the trading activity in crude oil paper markets, shipping costs, as well as the stock market development in the US and Europe. After the break in 2010, the influence of paper markets activity, shipping costs, and trading volumes has gained in importance.