Stocks are off to a mixed start on Wall Street ahead of a speech by Federal Reserve Chair Janet Yellen later in the day.
Investors will be listening for clues Friday on whether the central bank will raise interest rates again later this month.
Several companies were moving after reporting their latest quarterly results.
Costco slid 3.6 percent after the warehouse club operator reported earnings that missed estimates.
Marvell Technology rose 2 percent after the semiconductor maker’s latest earnings and outlook beat estimates.
The Standard & Poor’s 500 index slipped a fraction to 2,381. The Dow Jones industrial average gained 27 points, or 0.1 percent, to 21,027. The Nasdaq composite gave up 3 points to 5,858.
Bond prices fell. The yield on the 10-year Treasury note rose to 2.49 percent.