Energy is leading the market in 2021 after a miserable year where it lost 32.6%. The energy sector of the S&P 500, as measured by the Energy Select Sector SPDR Fund (XLE), is already up 39.8% through March 5, which dwarfs the S&P 500âs return of 0.33% so far this year. Source: MarketWatch Investors must ask: Why is the energy sector outperforming, how does the petroleum refining industry that drives it operate and can the momentum continue? This comprehensive research report introduces the petroleum refining industry and breaks down its structure, firm conduct, performance and trends to watch going forward. Industry introduction The petroleum refining industry encompasses the market involved in products derived from the refining of crude oil. These products span a wide range including gasoline, diesel, jet fuel, petrochemicals like benzene and toluene, and heavy products such as asphalt.Â