The S&P 500 and the Dow were pressured by declines in financial stocks, while consumer discretionary shares lifted the Nasdaq.
The S&P 500 financial index .SPSY slipped 0.48 percent, weighed down by Berkshire Hathaway (BRKa.N) and JPMorgan (JPM.N). The sector had risen more than 1 percent a day earlier.
However, losses on the S&P and the Dow were limited by a rise in energy shares due to a 2 percent gain in oil prices. The S&P 500 energy index .SPNY was up 1.1 percent after data showed a smaller-than-expected build in U.S. crude stockpiles.
With an August target date set for a highly anticipated U.S. tax reform bill and the quarter nearing an end, analysts expect the market to trade in a tight range.
"We're going to be fairly range-bound as we get to the earnings season or until there is some significant development on tax reforms," said Michael Scanlon, portfolio manager at Manulife Asset Management in Boston.
The reaction of U.S. markets to Britain formally initiating a process to separate from the European Union was muted.
At 12:35 a.m. EDT the Dow Jones industrial average .DJI was down 53.02 points, or 0.26 percent, at 20,648.48, the S&P 500 .SPX was up 0.74 points, or 0.03 percent, at 2,359.31 and the Nasdaq Composite .IXIC was up 15.03 points, or 0.26 percent, at 5,890.17.
Amazon.com (AMZN.O) hit an all-time high of $870.88 and gave the biggest boost to the Nasdaq.
Vertex Pharmaceuticals, (VRTX.O) jumped 23 percent to $110.25 after its cystic fibrosis treatment succeeded in a late-stage trial.
UnitedHealth (UNH.N), which rose for the first time in nine days on Tuesday, was off 1.4 percent.
Advancing issues outnumbered decliners on the NYSE by 1,787 to 1,079. On the Nasdaq, 1,618 issues rose and 1,136 fell.
The S&P 500 index showed 11 52-week highs and one low, while the Nasdaq recorded 66 highs and 21 lows.
(Reporting by Yashaswini Swamynathan in Bengaluru; Editing by Anil D'Silva)