NEW YORK ( TheStreet) -- TransAtlantic Petroleum ( TAT), Forest Oil ( FST) and Berry Petroleum Company ( BRY) showed strength this past week, whereas Yingli Green Energy Holdings ( YGE), SunPower ( SPWRA) and Frontline ( FRO) eroded substantial value.TransAtlantic Petroleum was the major gainer last week, jumping 30.9%. Crude oil prices rallied last week after the European Central Bank (ECB) cut interest rates in a surprise move. Also, an options broker at GA Global Markets said the dollar will continue soft, while commodities like energy and precious metals will remain upbeat. Forest Oil climbed 25% after the company recorded favorable quarterly results and subsequent to Bank of America upgrading the stock to buy rating from neutral. For the third quarter, the company recorded net profit of $82.8 million, or 72 cents per a share, up from $68.9 million, or 60 cents per share in the year-ago quarter. For the fourth quarter of 2011, the company estimates sales volume guidance of 335 Mmcfe per day. Berry Petroleum Company accumulated 14% at close last week. Plains Exploration & Production ( PXP) followed gaining 12.3%. For the third quarter of 2011, the company posted revenue of $501.8 million, vs. $387.8 million in the year-ago quarter. Net cash generated by operating activities was $345.2 million, a 70% increase over 2010 third quarter. Average daily sales volume increased 15% year-over-year, while average daily liquids sales volume grew 9%. Exterran Holdings ( EXH) advanced 12% at close last week. The company announced last week it estimates to incur additional charges with regard to the cost reduction program of almost $11 million to $14 million in the fourth quarter of 2011 through fiscal 2012. RPC ( RES) moved up 9% after Canaccord Genuity upgraded the stock's rating to buy from hold with a price target of $24 indicating 17.1% upside from current levels, citing positive third-quarter results and under performance relative to peers. Reporting positive quarterly earnings last week, Ultra Petroleum ( UPL) and EOG Resources ( EOG) appreciated 7.2% and 6.8%, respectively. For the third quarter of 2011, UPL recorded 20% increase in adjusted earnings per share to $110.3 million, or 72 cents per share. Operating cash flow for the same period increased 29% to $257.3 million. Also, EOG recorded earnings per share of 83 cents, vs. 78 cents estimated by a Reuters analysts' poll. Revenue soared 82.4% with crude oil production increasing 54%. Among losers, Yingli Green Energy Holdings was at the helm last week, down 22.8%. SunPower followed losing 17.2%. SunPower recorded a more than double loss of $370 million as compared to $$147.9 million loss in the second quarter of 2011.. Also, the company has narrowed its full-year revenue guidance to $2.4 billion to $2.45 billion from a previous view of $2.8 billion to $2.95 billion. Earnings per share are seen in the range of a loss of 5 cents to earnings of 20 cents, which compares to the earlier range of 75 cents to $1.25. Frontline lost 16.6% at close last week. Transocean ( RIG) dropped 16.5% after reporting third quarter 2011loss of $71 million, or 22 cents per share, compared to net profit of $368 million, or $1.15 per share, in the year-ago quarter. Also, operating margin dropped to 12% from 27.8% for the same period. Besides, Weeden & Co. downgraded the stock from buy to hold last Thursday afternoon. The analyst's price target was reduced from $70 to $55. Niska Gas Storage Partners ( NKA) plunged 147% at close last week after its second quarter fiscal 2012 quarterly profit declined 12% due to weak natural gas prices. Total realized revenues dipped 9%. Major solar stocks, LDK Solar ( LDK), Trina Solar ( TSL) and JA Solar Holdings ( JASO) slipped 12.9% each last week.