NEW YORK (TheStreet) -- Anadarko Petroleum (APC), Marathon Oil (MRO) and Murphy Oil (MUR) are among energy stocks that received an adjusted earnings per share upgrade on fourth-quarter estimates over the past four weeks.The earnings for these 10 energy stocks were upgraded in the range of 4%-25% during the past four weeks. In comparison, analysts upgraded earnings per share of Exxon Mobil ( XOM), Chevron ( CVX), BP ( BP) and ConocoPhillips ( COP) by around 3.1%, 3.2%, 3.9% and 1.7%, respectively. We have not included TransAtlantic Petroleum ( TAT), Holly ( HOC), Valero Energy ( VLO), Penn West Energy Trust ( PWE), Nexen ( NXY) and Petrobras ( PBR) in this list, although they received a weighty EPS revision, because only a few analysts cover these stocks for adjusted earnings per share upgrade. Additionally, we have not included Atlas Energy ( ATLS), which has a downside of 2% and buy ratings of 9%, and Concho Resources ( CXO), which has a downside of 2%, as per the estimated price target of analysts polled by Bloomberg. Analysts expect the following 10 stocks to provide attractive investment returns during 2011, based on the upside implied from their respective 12-month price targets. Additionally, most of these stocks received favorable buy recommendations. The stocks are stacked by percentage of EPS upgrade in ascending order.