Markets Insider
All the three major indexes had opened higher in New York, with the Nasdaq Composite hitting yet another record high, lifted by Apple.
But at 11:02 a.m. ET, the Dow Jones Industrial Average was down 115 points, or 0.5%. The S&P 500 was down 13 points (0.57%) and the Nasdaq was down 41 points (0.7%).
Earlier, Apple rose 0.66 percent to an all-time high of $142.40 after the company unveiled a new version of its iPad tablet.
Investor optimism was also boosted by French centrist Emmanuel Macron's performance in a television debate that boosted a view that he would win the presidential election over the far-right's Marine Le Pen.
The expectations boosted sentiment across Europe, with stock markets across the region broadly firmer.
Global investors have been worried about increasing protectionism, following the Brexit vote and President Donald Trump's election. Last week, the G20 leaders dropped a pledge to keep global trade free and open.
Investors will keep an eye on speeches by several Federal Reserve officials for clues on the path of future interest rate hikes after the central bank last week raised rates for the first time this year.
The Fed stuck to its outlook for two more hikes this year, instead of the three expected by the market.
Bank of Kansas City President Esther George and Cleveland Fed chief Loretta Mester are scheduled to speak later in the day, while Boston Fed head Eric Rosengren will release the text of his speech.
"Investors continue to expect two more rate hikes this year, although the odds have slipped slightly since last week," said Craig Erlam, senior market analyst at online forex broker Oanda in London.
"That said, I still expect the Federal Reserve tightening cycle to be much more aggressive than other central banks over the next couple of years."
Oil prices climbed on Tuesday, helped by expectations that an OPEC-led output cut would be extended beyond June but gains were pegged back by concerns about persistently high crude inventories.
Shares of General Mills slipped 0.2 percent to $60.13 after the Cheerios maker's quarterly sales missed expectations.
Esperion Therapeutics jumped 15.1 percent to $47.48 after J.P. Morgan raised its price target on the stock.
FedEx and Dow-component Nike, which are due to report quarterly results after markets close, both edged up about 0.6 percent.
Advancing issues outnumbered decliners on the NYSE by 1,822 to 741. On the Nasdaq, 1,518 issues rose and 715 fell.
The S&P 500 index showed 22 new 52-week highs and no new lows, while the Nasdaq recorded 55 new highs and 12 new lows.