On Apr 13, Zacks Investment Research downgraded leading oil and gas Exploration and Production (E&P) companyWhiting Petroleum Corp. WLLto a Zacks Rank #5 (Strong Sell). Post downgrade, the company is among the bottom 5% of all stocks that are ranked by Zacks.Why the Downgrade?Being a leading upstream energy firm, Whiting Petroleum’s business is dependent on commodity prices. The company, like its peers, has been affected by falling commodity prices as it has able to extract less value for its products.Both oil and natural gas prices have been weak for a considerable length of time, primarily owing to a supply glut in the face of lackluster global demand. This weakness in commodity prices has adversely affected the company’s financials. Notably, the odds of crude prices rallying in the near term remain bleak. Hence, we estimate the company to post a loss of $2.30 per share in 2016. Detailed AnalysisWhile a brief rally has helped U.S. oil price rebound from its 12-year low of $26.21 reached in Feb, at around $41 a barrel they still remain around 35% down from 2015 highs and far below the breakeven price for many energy companies. Natural gas, on the other hand, is trading around $2 per MMBtu, substantially below the peak of $13.50 per MMBtu in 2008. This significant decline in commodity prices has adversely affected all the major upstream players and Whiting Petroleum is no exception.With oil price expected to remain low, Whiting Petroleum has projected a capital budget of $500 million in 2016. This marks a massive 80% decline, year over year. The company also estimates an inventory of 73 drilled uncompleted wells in the Williston Basin Bakken play and 95 drilled uncompleted wells in the DJ Basin Niobrara play. A cutback in capital spending and rise in inventory of drilled uncompleted wells in order to improve profitability and strengthen balance sheet is likely to negatively impact the company’s production volumes, thereby aggravating woes.These bearish factors have prompted downward estimate revisions for the company of late. In fact, over the last 60 days, ten out of 13 analysts lowered their estimates for the current quarter. This resulted in the Zacks Consensus Estimate widening from a loss of 49 cents per share to a loss of 72 cents. Also, 16 out of 17 analysts have rendered negative estimate revisions on the stock for 2016 over the same period. This has resulted in the Zacks Consensus Estimate widening from a loss of $1.21 per share to a loss of $2.30.Stocks That Warrant a LookThough we expect Whiting Petroleumto perform below its peers and industry levels in the coming months and see little reason for investors to own the stock, one can consider better-ranked players in the oil and gas E&P industry like Antero Resources Corporation AR, Vanguard Natural Resources, LLC VNR and World Point Terminals, LP WPT. All these stocks sport a Zacks Rank #1 (Strong Buy).Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report >>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report VANGUARD NATURL (VNR): Free Stock Analysis Report WHITING PETROLM (WLL): Free Stock Analysis Report WORLD POINT TER (WPT): Free Stock Analysis Report ANTERO RESOURCE (AR): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research