May 8, 2013 (Shareholders Foundation) - An investigation on behalf of investors in Pioneer Southwest Energy Partners L.P. (NYSE:PSE) units was announced concerning whether the offer by Pioneer Natural Resources Company to acquire Pioneer Southwest Energy Partners L.P. for a value of approximately $29.83 per NYSE:PSE unit and the takeover process are unfair to investors in Pioneer Southwest Energy Partners L.P.

The investigation by a law firm concerns whether certain officers and directors of Pioneer Southwest Energy Partners L.P. breached their fiduciary duties owed to NYSE:PSE investors in connection with the proposed acquisition.

On May. 7, 2013, Pioneer Southwest Energy Partners L.P. (NYSE:PSE) announced that the chairman of the Conflicts Committee of the board of directors of Pioneer Southwest Energy Partners L.P.s general partner received a proposal from Pioneer Natural Resources Company (NYSE: PXD) whereby Pioneer Natural Resources Company would acquire all of the outstanding, publicly-held Pioneer Southwest Energy Partners L.P. common units Pioneer Natural Resources Company does not already own through a stock-for-unit exchange. Subject to negotiation and execution of a definitive agreement, Pioneer Natural Resources Company is proposing consideration of 0.2234 of a share of Pioneer Natural Resources Company common stock for each outstanding publicly-held Pioneer Southwest Energy Partners L.P. common unit. Based on a closing price of NYSE:PDX shares of $133.54 on May 7, 2013, the offer implies a value of $29.83 per NYSE:PSE unit.

However, given that NYSE:PSE units jumped after the announcement to as high as $32.25 per unit and that units of Pioneer Southwest Energy Partners L.P. (NYSE:PSE) traded in 2011 as high as $35.53, the investigation a law firm concerns whether the offer is too low for:PSE unitholders.

Furthermore, given that Pioneer Natural Resources Company owns 100% percent of the general partner of Pioneer Southwest Energy Partners L.P. and owns approximately 52.4% of the 35,713,700 outstanding common units of Pioneer Southwest Energy Partners L.P., the investigation focuses on whether the Pioneer Southwest Energy Partners L.P. Board of Directors undertook an adequate sales process, adequately shopped the company before entering into the transaction, maximized shareholder value by negotiating the best price, and acted in the shareholders' best interests in connection with the proposed sale.

On May 8, 2013, NYSE:PSE units closed at $32.20.