Declines in Exxon Mobil XOM.N and Chevron CVX.N were among the biggest individual drags on the S&P 500. By Lewis Krauskopf, Devik Jain and Sruthi Shankar June 23 (Reuters) - The S&P 500 ended higher on Thursday after a day of choppy trading, as gains in defensive and tech shares countered declines for economically sensitive groups as worries persisted about a potential recession. In his second day of testifying before Congress, U.S. central bank chief Jerome Powell said the Fed's commitment to reining in 40-year-high inflation is "unconditional" but also comes with the risk of higher unemployment.