NEW YORK (TheStreet) -- Pride International (PDE), Lufkin Industries (LUFK) and Frontier Oil (FTO) were the top gainers, while Petrobras Argentina (PZE), Nexen (NXY) and Southwestern Energy (SWN) headed the losers' list last week.Pride International gained 16.5%, topping energy gainers, after Ensco ( ESV) announced to buy Pride for $41.60 per share, representing a 21% premium to Prideâ¿¿s Feb. 04 closing price. On Friday, the stock closed at $40.08. Later, Wells Fargo raised the stock to outperform from market perform and its valuation for Pride to $45-$46 from $34-$36. However Macquarie Research, BMO Capital Markets, Barclays, Tudor Pickering, Howard Weil and Capital One Southcoast downgraded the stock preventing a further upside in the stock price last week. Lufkin Industries swung 14.1% higher after the company guided 2011 earnings per share at $2.5-$3.0 vs. consensus $2.67 and revenues at $800-$850 million vs. consensus $820.5 million. During the week, Johnson Rice initiated coverage on the stock with an overweight rating, while Howard Weil raised the stock to market outperform from market perform. Frontier oil gained 9.9% after BofA Merrill Lynch upgraded the stock to buy from neutral. Oil States International ( OIS) rose 9.0% after receiving a three-year contract valued $14 million to supply offshore marine cranes to PTT Exploration and Production. JA Solar Holdings ( JASO) climbed 6.6% last week, leading the pack of solar gainers. Other solar stocks such as First Solar International ( FSLR), Yingli Green Energy Holdings ( YGE), Trina Solar ( TSL), ReneSola ( SOL), GT Solar International ( SOLR) and LDK Solar ( LDK) advanced around 5.2%, 2.6%, 1.9%, 1.7%, 0.9% and 0.7%, respectively. BG Group (OTC: BRGYY) surged 6.5% after reporting a 13% increase in fourth-quarter profit to $1.06 billion, as revenue and other income grew 1.2% to $4.36 billion on improved realized prices. Meanwhile, the company has revised production estimates in Brazilâ¿¿s Santos Basin and the forecast for U.S. Shale gas production. Precision Drilling ( PDS) rose 6.4% last week. For 2010 fourth quarter, the company reported diluted earnings per share of 2 cents vs. a loss per share of 9 cents a year-ago. Revenues came in at C$435.5 million vs. consensus C$369.3 million, up from C$286.1 million reported for 2009 fourth quarter. Meanwhile, Raymond James has upgraded the stock to outperform from market perform. Core Laboratories ( CLB) advanced 6.0% after reporting 2010 fourth quarter earnings per share ex-items at 84 cents vs. estimates of 81 cents, while revenues came in $208.2 million vs. estimates of $206.7 million. Atwood Oceanics ( ATW) climbed 5.6% after Morgan Stanley upgraded the stock to overweight from underweight. Among major movers, Chesapeake Energy ( CHK) gained 2.6% last week. Argus Research upgraded the stock to hold from sell, while Ticonderoga Securities and Global Hunter Securities raised the rating to buy from hold. Meanwhile, Apache ( APA) added around 2.5% after tension eased in Egypt. Other winners include Atlas Pipeline Partners ( APL), SandRidge Energy ( SD), Brigham Exploration ( BEXP) and CARBO Ceramics ( CRR), up 9.8%, 9.5%, 9.2% and 5.7%, respectively. Petrobras Argentina was the top loser, erasing 8.1% value and continuing its losing streak from the penultimate week. Nexen edged 7.0% lower after Cormark Securities cut its rating on the stock to market perform from buy. CNOOC ( CEO) declined around 5.9% despite BNP Paribas raising the stock to buy from hold on attractive valuations. Premier Oil (OTC: PMOIY) dipped around 5.4% after evolution Securities downgraded the stock to add from buy. Similarly, Statoil ( STO) shed 5.3% after Macquarie Research downgraded the stock to neutral. Newfield Exploration ( NFX) was down 5.1% after Jefferies downgraded the stock to hold from buy, citing valuations and lowered price target to $70 from $76. Among others, FMC Technologies ( FTI), PetroChina ( PTR), Petroleo Brasileiro ( PBR) and Exterran Holdings ( EXH) dipped 5.9%, 5.6%, 4.9% and 4.4%, respectively.