Stock Trading History of Berg Mark Stephen

The following table details the trading activities (stock purchases, stock sales, and stock option exercises) reported to the Securities and Exchange Commission (SEC) by insider Berg Mark Stephen since year 2005. The trader's CIK number is 1238881. At the time of this reporting, Berg Mark Stephen is the EVP, General Counsel of Pioneer Southwest Energy Partners L.p. . (stock ticker symbol PSE). See this page for all insider trading activities at Pioneer Southwest Energy Partners L.p. .

Stock purchases, sales, and option exercises reported by insider *Berg Mark Stephen* since 2005.
Trade Date	Symbol	Company Name (Issuer)	Trade Type	Shares	Price ($)	Value ($)
2008-05-06	PSE	Pioneer Southwest Energy Partners L.p.	Purchase	10,000	19.00	190,000

Insider trading activities including stock purchases, stock sales, and option exercises listed in the above table cannot be completely guaranteed as to their accuracy. For more information regarding the trades made by Berg Mark Stephen (EVP, General Counsel of Pioneer Southwest Energy Partners L.p. at the time of this reporting) see the Securities and Exchange Commission (SEC) website.