NEW YORK ( TheStreet) -- Atlas Pipeline Partners ( APL), Rosetta Resources ( ROSE), Ensign Energy(ESVIF) and PTT Public (PUTRF) were top performers last week, while Aventine Renewable Energy Holdings ( AVRW), OAO Tatneft (OAOFY) and Polski Koncern (PSKNY) lost substantial ground.Atlas Pipeline Partners topped the charts, gaining 12%. The company announced major organic expansions as APL's systems are operating at around 100% of capacity. The projects include expansion of the Western Oklahoma system, the restart of the cryogenic skid at Midkiff in West Texas and expansion of the Velma system. The capital expenditure is expected to increase by $400 million for 2011-2012 period. Rosetta Resources rose 11% after analyst Irene Haas of Wunderlich Securities upgraded the stock to buy from hold. The stock's 12-month target price is $57 per share. Ensign Energy rose 8.4% during the week. The analysts at Canaccord raised the stock to buy from hold. PTT Public surged 6.4% on good quarterly results. The company's net profit hit record high, beating analyst estimates in the first quarter of 2011. Overall, reported revenue was up 20% on the gains from refinery and petrochemical segments. GT Solar ( SOLR) moved up 6.1%. The company announced three new orders totaling $91 million for its sapphire crystallization furnaces. Players like Atlas Energy ( ATLS) and Legacy Reserves ( LGCY), were up 5.8% and 4.8%, respectively. Gran Tierra Energy ( GTE) rose 4.1%. David Popowich of Macquarie Research upgraded the stock to outperform from neutral. The stock's 12-month target price is $9.5 per share. Other movers include China Oilfield Services (CHOLY), Penn West Petroleum ( PWE), Inter Oil Corporation ( IOC), YPF SA ( YPF) and Newfield Exploration ( NFX), up 4.1%, 4%, 3.9%, 3.8% and 3.7%, respectively. Precision Drilling Corporation ( PDS) rose 3.5%. Analyst Scott Treadwell of Macquarie upgraded the stock to outperform from neutral. The stock's 12-month target price is $17 per share. Others stocks like Pioneer Natural Resources ( PXD), Cameron International Corporation ( CAM), Carbo Ceramics ( CRR), Dril-Quip ( DRQ), Oceaneering International ( OII), Marathon Oil Corporation ( MRO), Quick Silver Resources ( KWK) and Teekay LNG partners ( TGP) posted gains in the range of 2.5% to 3.5% during the week. Aventine Renewable Energy Holdings was the top loser, declined 20% during the week. OAO Tatneft lost 10.2% after reports of export duty increase by Russian Government. According to Bloomberg, Russia may increase export taxes on gasoline feedstock used if fuel shortages in the domestic market persist.
Polski Koncern declined 9.1% during the week. Nexen ( NXY) dipped 8.7% after TD cut Nexen price target on account of a production halt at its Yemen operations due to a labour disruption and curtailed output at its Buzzard assets in the North Sea. The brokerage cut price target by $1 to $26 and maintained a hold rating on the stock. BG Group (BRGYY) declined 8.2% for the week after earnings came below analyst expectations. EPS for the quarter represented a sequential EPS decline of 4% and year-over-year decline of 10%. Net Income for the first quarter stood at $1.014 billion, an average 13% below market consensus of $1.172 billion. Surgutneftegas OAO (SGTPY) dipped 7.9% after expectation of a export tax by Russia on gasoline feedstock, heavy oil product and light oil products. Other underperformers were Surgutneftegas OAO (SGTZY), Yingli Green Energy ( YGE) and LDK Solar ( LDK), erasing 7.5%, 6.9% and 6.9%, respectively. Canadian Natural Resource ( CNQ) accumulated losses of 6.7% on lower than expected first quarter results. The company posted a plunge of 94% in first-quarter profits on a combination of fire at Horizon oil sands and a higher tax rate in the United Kingdom. Among others, OGX Petroleo (OGXPY), Inpex Corporation (IPXHY), Energy Transfer Equity ( ETE) and Tesoro Corporation ( TSO) eroded 6.5%, 6.4%, 6.3% and 5.9% in value, respectively.