X0306 4 2013-12-17 1 0001407463 Pioneer Southwest Energy Partners L.P. PSE 0001238881 BERG MARK STEPHEN 5205 N. O'CONNOR BLVD., SUITE 200 IRVING TX 75039 0 1 0 0 EVP, General Counsel Common Units 2013-12-17 4 D 0 11426 D 0 D On December 17, 2013, the Issuer merged with a subsidiary of Pioneer Natural Resources Company ("PXD") and each publicly held common unit of the Issuer was converted into the right to receive 0.2325 of a share of PXD common stock. Pursuant to the merger, common units of the Issuer held by the reporting person were converted into 2,657 shares of PXD common stock. On December 17, 2013, the closing price of Issuer common units was $42.50 and the closing price of shares of PXD common stock was $182.43. By: Mark H. Kleinman, Attorney-in-Fact For Mark S. Berg 2013-12-18