NEW YORK (TheStreet) -- Trina Solar (TSL), Renesola (SOL), Tesoro Corp (TSO), Yingli Green Energy Holding (YGE), Oceaneering International (OII) and China Petroleum & Chemical Corp (SNP) gained last week, whereas Frontline Ltd/Bermuda (FRO), Quicksilver Resources (KWK), Comstock Resources (CRK), First Oil (FST) and Teekay Offshore Partners (TOO) eroded substantial value.Trina Solar led the pack of winners, up 20.1%. Ahmar Zaman, analyst at Piper Jaffray, has raised the stock to overweight from neutral with a 12-month target price of $19 per share. ReneSola jumped 16.4% after it announced to repurchase up to $100 million in aggregate value of the company's outstanding ordinary shares. Yingli Green Energy Holding ( YGE) rallied 16.3% on an upgrade to neutral from underweight from analysts at HSBC. Piper Jaffray has raised the stock's rating to overweight from neutral, and Avian Securities has upped its rating to positive from negative. Tesoro Corp gained 15.8% after Mark Gilman, an equity analyst at Benchmark, raised the stock to buy from sell. The stock has a 12-month target price of $25 per share. LDK Solar ( LDK) moved up 15.4%, ahead of its second-quarter earnings release on August 29. The company recently lowered its guidance estimate for the second quarter, and fiscal 2011. CARBO Ceramics ( CRR) rose 13.9% after analysts at Dahlman Rose increased the stock's price target to $229 per share from $216, maintaining a buy rating on it. The company intends to build a $100 million plant in Jenkins County, pending environmental permits that are expected in October, The Millen News reports. First Solar ( FSLR) gained 13.6% after analysts at Collins Stewart upgraded the stock to buy from neutral with a price target of $132 per share. Oceaneering International ( OII) increased 13% during this past week. Other movers last week included Complete Production Services ( CPX) (+12.3%), Valero Energy ( VLO) (+10.9%), Helix Energy Solutions Group ( HLX) (+10%), Cameron International ( CAM) (+9.8%), Ensco ( ESV) (+9.2%), Helmerich & Payne ( HP) (+9.1%), Halliburton ( HAL) (+9%), Precision Drilling Corp ( PDS) (+8.1%) and Cabot Oil & Gas ( COG) (+ 8%). China Petroleum & Chemical Corp ( SNP) increased 8% for the week. FMC Technologies ( FTI) grew 8%, Key Energy Services ( KEG) moved up 7.9%, Nabors Industries ( NBR) gained 7.7%, Dril-Quip Inc ( DRQ) rose 7.5% and RPC Inc ( RES) closed 7.3% higher. ENI SpA ( E) rose 7.2% this past week. The company has announced plans to supply gasoline and diesel to Libya in the next few days. ENI's chief executive Paolo Scaroni said the company will increase natural gas production at the earliest, while resumption of oil output would take another 6 to 18 months, Bloomberg reports.
Quicksilver Resources topped the decliners' last week, plunging 9.4%. Frontline shed 5.8%. Comstock Resources and Forest Oil erased 5.7% and 5%, respectively, this past week. Other losers were Teekay Offshore Partners ( TOO) (-3.4%), Boardwalk Pipeline Partners ( BWP) (-3.3%), PAA Natural Gas Storage ( PNG) (-2.7%) and Ultra Petroleum Corp ( UPL) (-1.8%). Enbridge Energy Management ( EEQ), InterOil Corp ( IOC), Teekay LNG Partners ( TGP) and Penn West Petroleum ( PWE) lost more than 1%.