Energy (XLE -1.1%) is the worst performing S&P sector today with refiners taking the biggest...

Energy (XLE -1.1%) is the worst performing S&P sector today with refiners taking the biggest hit following Marathon Petroleum's (MPC -4.9%) profit warning, which came on the heels of Valero's (VLO -2%) warning a few days ago as higher oil prices alongside flattish product pricing isn't a great combination. Others: Phillips 66 (PSX -3.3%), Tesoro (TSO -2.6%).