06.06.201721:43:00UTC+00U.S. Stocks Drop as UK Vote, Comey Testimony Eyed

Wall Street inched lower on Tuesday as investors passed up riskier assets ahead of Thursday which involves Britain going to the polls and former FBI director James Comey's testimony before Congress.

The Dow Jones industrial average slipped 0.23 percent to end at 21,136.23, as Wal-Mart led losses while Exxon Mobil was the best performer. The S&P 500 dropped 0.28 percent to close at 2,429.33, with consumer discretionary leading nine sectors down as energy and materials were the only gainers. The Nasdaq composite fell 0.33 percent to finish at 6,275.06.

Investors will also focus on the European Central Bank's meeting, where policymakers are seen to take a more favorable outlook of the economy, according to sources.

Eight of the 11 major S&P 500 sectors traded lower, with the financial index's 0.35 percent decline leading losses while the drop in bond yields also added pressure.

Among shares active in corporate news, HD Supply Holdings tumbled 19 percent to a near seven-month low of $33.41 after the industrial distributor said it will sell a unit to private equity company for $2.5 billion. The stock pulled down the Nasdaq.