The Oils-Energy group has plenty of great stocks, but investors should always be looking for companies that are outperforming their peers. Marathon Oil (MRO) is a stock that can certainly grab the attention of many investors, but do its recent returns compare favorably to the sector as a whole? By taking a look at the stock's year-to-date performance in comparison to its Oils-Energy peers, we might be able to answer that question.Marathon Oil is a member of the Oils-Energy sector. This group includes 255 individual stocks and currently holds a Zacks Sector Rank of #1. The Zacks Sector Rank considers 16 different sector groups. The average Zacks Rank of the individual stocks within the groups is measured, and the sectors are listed from best to worst.The Zacks Rank is a proven system that emphasizes earnings estimates and estimate revisions, highlighting a variety of stocks that are displaying the right characteristics to beat the market over the next one to three months. Marathon Oil is currently sporting a Zacks Rank of #1 (Strong Buy).The Zacks Consensus Estimate for MRO's full-year earnings has moved 22.6% higher within the past quarter. This shows that analyst sentiment has improved and the company's earnings outlook is stronger.Our latest available data shows that MRO has returned about 141.2% since the start of the calendar year. At the same time, Oils-Energy stocks have gained an average of 36.2%. This means that Marathon Oil is outperforming the sector as a whole this year.Breaking things down more, Marathon Oil is a member of the Oil and Gas - Integrated - United States industry, which includes 12 individual companies and currently sits at #29 in the Zacks Industry Rank. On average, stocks in this group have gained 87.3% this year, meaning that MRO is performing better in terms of year-to-date returns. Infrastructure Stock Boom to Sweep America A massive push to rebuild the crumbling U.S. infrastructure will soon be underway. It’s bipartisan, urgent, and inevitable. Trillions will be spent. Fortunes will be made. The only question is “Will you get into the right stocks early when their growth potential is greatest?” Zacks has released a Special Report to help you do just that, and today it’s free. Discover 7 special companies that look to gain the most from construction and repair to roads, bridges, and buildings, plus cargo hauling and energy transformation on an almost unimaginable scale.Download FREE: How to Profit from Trillions on Spending for Infrastructure >>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 Marathon Oil Corporation (MRO): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research