The general partner of Pioneer Southwest Energy Partners LP (NYSE: PSE) received a proposal from Pioneer Natural Resources Co. (NYSE: PXD) whereby Pioneer would acquire all of the outstanding, publicly-held Pioneer Southwest common units Pioneer does not already own through a stock-for-unit exchange.

Subject to negotiation and execution of a definitive agreement, Pioneer is proposing consideration of 0.2234 of a share of Pioneer common stock for each outstanding publicly-held Pioneer Southwest common unit. In proposing the 0.2234 exchange ratio, Pioneer stated that it has assumed that a regular quarterly common unit distribution of US $0.52 per common unit will be declared in July and that, thereafter, common unit distributions will be suspended while the transaction is pending. The proposed transaction would be structured as a merger of Pioneer Southwest with a wholly owned subsidiary of Pioneer. The proposal was referred to the conflicts committee of the general partner, which will study, review and evaluate the proposal. There can be no assurance that a definitive agreement will be executed or that any transaction will be approved or consummated.

Pioneer owns 100% percent of the general partner of Pioneer Southwest and owns 52.4% of the 35,713,700 outstanding common units of Pioneer Southwest.

Pioneer Southwest Energy Partners LP is a Delaware limited partnership focused on the acquisition, exploration, and development of oil and gas properties in the US. The company is based in Irving, Texas, and has current production and drilling operations in the Spraberry field in West Texas.

Pioneer Natural Resources Com. operates as an independent oil and gas E&P company in the US. The company is headquartered in Irving, Texas.