PIONEER SOUTHWEST ENERGY

On December 17, 2013, Pioneer Southwest Energy Partners L.P. ("Pioneer Southwest") merged with a wholly-owned subsidiary of Pioneer Natural Resources Company ("Pioneer"). Under the merger agreement, each Pioneer Southwest unitholder eligible to receive the merger consideration became entitled to receive 0.2325 of a share of Pioneer common stock for each Pioneer Southwest common unit owned by such unitholder, plus, after aggregating all fractions of shares to which such unitholder would be entitl... ed, a whole share of Pioneer common stock in lieu of any fractional share of Pioneer common stock otherwise issuable to such unitholder. Shares of Pioneer’s common stock trade on the New York Stock Exchange under the ticker symbol "PXD." Pioneer Southwest’s common units traded on the New York Stock Exchange under the ticker symbol "PSE" until the close of business on December 17, 2013.More