NEW YORK ( TheStreet) -- MarkWest Energy Partners ( MWE), Copano Energy ( CPNO) and Quicksilver Resources ( KWK) showed strength this past week, whereas ReneSola ( SOL), LDK Solar ( LDK) and JA Solar Holdings ( JASO) pared significant losses.MarkWest Energy Partners was the top gainer last week, jumping 4.9% after it was upgraded from market perform to outperform at Wells Fargo & Company. Copano Energy followed gaining 4.2% after Barclays maintained an equal weight rating on the stock. Quicksilver Resources climbed 3.4% last week after it was known that the company has ramped up its Barnett Shale production by almost 19% in the third quarter. Enbridge Energy Partners ( EEP) accumulated 3.2%. It was known last week that the company's vice president (VP) for Natural Gas Marketing bought 500 shares of the company for $30.12, while VP for Commercial Activities purchased 1,000 shares for $30.10. Lufkin Industries ( LUFK) advanced 3%. Last week, Baker Hughes said it is seeking deals to reap higher benefits from the shale-oil exploration boom in the U.S., indicating that Key Energy Services and Lufkin are on its wish list. Lufkin, because the company's pump jacks are used to pump oil out of the ground when an older well loses its natural pressure, would support Baker Hughes in expanding its range of services. Petrobras Argentina ( PZE) and Magellan Midstream Partners ( MMP) moved up 2.9% each last week. Zacks Investment Research reaffirmed its neutral rating on the stock last week with a price target of $66, indicating 1.5% upside from current levels. Atlas Energy ( ATLS) and Atlas Pipeline Partners ( APL) gained 2.8% and 2.6% at close last week. Citigroup raised its price target on APL to $40 last week, indicating 13.3% upside from current levels. Mid-week, APL announced that it has priced an add-on private offering of $150 million aggregate principal amount of its 8.75% Senior Notes due 2018, up from the earlier $125 million. The company plans to use the proceeds to repay a portion of the outstanding indebtedness under its credit facility. ReneSola was at the helm of losers last week, wiping out 21.1% on concerns regarding market demand. Additionally, as per a research report released last week, the U.S.-China trade dispute would decline the demand for solar products from companies like JA Solar and ReneSola. Moreover, if the protests over China's subsidies prove successful, a duty would be charged on solar equipment, which could impact the company's operations. JA Solar Holdings plunged 17.8% this past week.