Key Takeaways An analyst's downgrade weighed on a high-flying utility stock on Tuesday, while an uptick in oil prices helped drive gains for an oilfield services giant and its peers. Shares of oilfield services firms Halliburton and Baker Hughes gained ground. Shares of a recently-hot utility company tumbled Tuesday as an analyst questioned their valuation, while oilfield services stocks were boosted by rising crude oil futures prices. Shares of the electric utility company dropped 6.3%. Shares of oilfield services giant Halliburton (HAL) rose 7.3%, notching the S&P 500's top daily performance, while Baker Hughes (BKR) gained 2.6%.