Energy is the best performing sector again this year as oil prices stay elevated thanks to continued supply-demand imbalances. The rally is now being driven by oilfield services stocks as many of these companies reported blockbuster profits recently.

Schlumberger (SLB Quick QuoteSLB - Free Report) , which rebranded as SLB last month, posted 28% year-over-year top-line growth, while Halliburton’s (HAL Quick QuoteHAL - Free Report) earnings more than doubled in the third quarter. After many years of underinvestment, energy giants like Exxon Mobil (XOM Quick QuoteXOM - Free Report) and Chevron (CVX Quick QuoteCVX - Free Report) are willing to spend more for technological enhancements, which benefits oil services companies.

The VanEck Oil Services ETF (OIH Quick QuoteOIH - Free Report) invests in 25 largest and most liquid oil services companies. Schlumberger, Halliburton and Baker Hughes (BKR Quick QuoteBKR - Free Report) are its top holdings.

The SPDR S&P Oil & Gas Equipment & Services ETF (XES Quick QuoteXES - Free Report) tracks an equal-weighted index and is tilted toward smaller companies. The iShares U.S. Oil Equipment & Services ETF (IEZ Quick QuoteIEZ - Free Report) follows a modified market-cap weighting methodology.

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