Editor's Note: TheStreet ratings do not represent the views of TheStreet's staff or its contributors. Ratings are established by computer based on metrics for performance (which includes growth, stock performance, efficiency and valuation) and risk (volatility and solvency). Companies with poor cash flow or high debt levels tend to earn lower ratings in our model All three major indices are trading up today with the Dow Jones Industrial Average ( ^DJI) trading up 54 points (0.4%) at 15,287 as of Friday, May 17, 2013, 12:54 PM ET. The NYSE advances/declines ratio sits at 1,992 issues advancing vs. 899 declining with 140 unchanged. The Basic Materials sector currently sits up 0.3% versus the S&P 500, which is up 0.5%. On the negative front, top decliners within the sector include Agnico Eagle Mines ( AEM), down 3.82, Franco-Nevada ( FNV), down 3.69, Newmont Mining Corporation ( NEM), down 3.21, Goldcorp ( GG), down 2.50 and Silver Wheaton Corporation ( SLW), down 2.28. Top gainers within the sector include Noble Corporation ( NE), up 2.8%, Marathon Petroleum ( MPC), up 2.9%, Continental Resources ( CLR), up 2.6%, ArcelorMittal ( MT), up 2.5% and Noble Energy ( NBL), up 2.1%. TheStreet Ratings group would like to highlight 3 stocks pushing the sector lower today: 3. Ecopetrol S.A ( EC) is one of the companies pushing the Basic Materials sector lower today. As of noon trading, Ecopetrol S.A is down $0.42 (-0.9%) to $44.41 on light volume Thus far, 196,901 shares of Ecopetrol S.A exchanged hands as compared to its average daily volume of 632,600 shares. The stock has ranged in price between $44.35-$44.93 after having opened the day at $44.90 as compared to the previous trading day's close of $44.83. Ecopetrol S.A., an integrated oil company, engages in the exploration, development, and production of crude oil and natural gas. As of December 31, 2011, its proved reserves of crude oil and natural gas totaled 1,856.7 million barrels of oil equivalent. Ecopetrol S.A has a market cap of $92.3 billion and is part of the energy industry. The company has a P/E ratio of 7.0, below the S&P 500 P/E ratio of 17.7. Shares are down 24.9% year to date as of the close of trading on Thursday. TheStreet Ratings rates Ecopetrol S.A as a buy. The company's strengths can be seen in multiple areas, such as its robust revenue growth, increase in net income, good cash flow from operations, expanding profit margins and largely solid financial position with reasonable debt levels by most measures. We feel these strengths outweigh the fact that the company has had lackluster performance in the stock itself. Get the full Ecopetrol S.A Ratings Report now. Exclusive Offer: Jim Cramer's 'go-to' small/mid-cap guru Bryan Ashenberg only buys stocks he thinks could return 50-100%. See his top picks for 14-days FREE.