NEW YORK ( TheStreet) -- Suntech Power Holdings ( STP), Frontier Oil ( FTO) and SunPower ( SPWRB) were the top gainers, while Seacor Holdings ( CKH), Tullow Oil and Newfield Exploration ( NFX) headed the losers' list last week.Suntech Power Holdings gained 20.2%, topping energy gainers, after the company secured an order from the UN for supplying $80 million worth of solar power systems over the next three years. Canaccord Genuity raised the stock to hold during the week. Frontier Oil swung 14.2% higher after Simmons & Company upgraded its rating on the stock to overweight from neutral. Separately, Deutsche bank raised its price target on Frontier oil to $30 from $23. Meanwhile, Dahlman Rose rated new buy with a price target of $33. On Friday, the stock closed at $28.12. SunPower surged 13.8% to reach 11-month highs after the company raised its 2011 earnings guidance to $2.0-$2.2 per share from the earlier $1.75-$2.05 issued in November. Nexen ( NXY) rose 13.2% last week. Cormark Securities upgraded Nexen to buy from market perform. Williams ( WMB), a pipeline operator, advanced 12.5% after the company announced plans to spin off its oil and natural gas exploration business. The initial public offering (IPO) is scheduled for the third quarter. Tesoro ( TSO) gained 10.2% during the week. Dahlman Rose rated the stock new buy with a target price of $34.0, up 40.7% from the current $24.1. Yingli Green Energy Holdings ( YGE) advanced 9.9% after reporting 2010 fourth quarter adjusted earnings per share at 57 cents vs. estimates of 47 cents, while revenue came in at $616.1 million vs. forecast $557.3 million. Yingli guided 2011 PV module shipments to 1,700MW-1,750MW from $1,062MW reported for 2010. Other solar stocks LDK Solar ( LDK), ReneSola ( SOL), Trina Solar ( TSL), GT Solar International ( SOLR), and First Solar International ( FSLR) advanced around 11.8%, 11.0%, 7.4%, 1.8%, and 1.3%, respectively. Nabors Industries ( NBR) rose 9.5% after reporting 2010 fourth quarter results. Adjusted earnings per share came in at 44 cents vs. consensus 38 cents, while operating revenue came in at $1.32 billion vs. estimated $1.27 billion. Jefferies raised its price target on the stock to $35 from $27, following the earnings announcement, reiterating its buy rating. Cimarex Energy ( XEC) rose 8.3% last week. Lazard capital raised its price target to $136 from $122, maintaining a buy rating, after the company announced fourth quarter results and a discovery in the Permian Basin. Meanwhile, Tudor Pickering upgraded the stock to buy from accumulate. However UBS cut its rating to neutral from buy.