NEW YORK (TheStreet) - SunPower (SPWRA), Southern Union (SUG), Chesapeake Midstream Partners (CHKM) and Bristow Group (BRS) clocked smart gains this week, while Frontline (FRO), Yingli Green Energy Holding (YGE), GT Solar International (SOLR) and Trina Solar (TSL) fared badly.Among the advancers, SunPower gained 10.1%. Southern Union topped the charts, jumping 2.7%. Williams has increased its bid on the company to about $5.6 billion in cash, topping its own previous bid of $5 billion in cash. Chesapeake Midstream Partners rose 1%, Bristow Group edged up 0.9% and PAA Natural Gas Storage ( PNG) moved 0.9% higher. Complete Production Services ( CPX) advanced 0.8% after equity analyst Brian Uhlmer at Global Hunter Securities raised the stock's rating to buy from accumulate with a target price of $45 per share. Williams Partners ( WPZ) advanced 0.7% on receiving an FERC endorsement to increase its Transco natural gas pipeline network by another 142,000 dekatherms of incremental firm natural gas transportation capacity by November 2012. EQT Corporation ( EQT) rose 0.5% after SunTrust Robinson's equity analyst Neal Dingmann upgraded the stock to buy from neutral with a 12-month target price of $68 per share. Frontline was the top lagger, shedding 14.2% after Morgan Stanley lowered its price target to $14.5 from $16. Credit Suisse has also cut the stock's price target from $18 per share to $12. Yingli Green Energy lost 14% after Goldman cut its rating on the stock to sell from neutral with a price target of $8 per share. GT Solar and Trina Solar declined 11.3% and 11.2%, respectively. CGG Veritas ( CGV) erased 10.9% after Barclays Capital downgraded the stock to equal weight from overweight with a target price of 31 euros per share. Reversing to the downside were Denbury Resources ( DNR) down 8.9%, EXCO Resources ( XCO) shedding 8.9%, Hess Corp ( HES) trimming 7.9%, Suntech Power Holdings ( STP) erasing 7.8%, Bill Barett Corporation ( BBG) losing 7.7% and Talisman Energy ( TLM) retreating by 7.6%. ReneSola ( SOL) lost 7.5% after the company lowered its second-quarter revenue guidance to the range of $235 million to $245 million, from $280 million to $300 million, owing to declining wafer prices. Statoil ASA ( STO) decreased 7.4% after Standard & Poor's equity analyst Christine Tiscareno downgraded the stock to sell from buy. Other losers included SandRidge Energy ( SD), First Solar ( FSLR), STR Holdings ( STRI), Eni SPA ( E), Oasis Petroleum ( OAS), Pioneer Natural Resources ( PXD) and YPF SA ( YPF).