Stocks on Wall Street topped 16,000 on the Dow Jones industrials index for the first time but closed lower.
The broader S&P 500 index went above 1800, as strength in overseas sharemarkets lead investors to push US stocks to fresh record highs, but closed down for the day.
The Dow Jones Industrial Average surged as high as 16,030 in early trading and stayed near that level for most of the day. Late in the session, however, investors had a rethink and the market lost more than 50 points to close at 15,976.02.
This was up 14.32 points, or 0.09%, up on Friday close, when the blue-chip index climbed 85 points, or 0.5%, to post the fifth record high close in six sessions and 38th record of the year.
It took the Dow 136 trading days to notch its latest 1000-point gain. That's the sixth-fastest rally of this magnitude in history.
Other indices are at or near all-time highs. The S&P 500 index was up 0.2% to 1802 in early trading but closed 6.65 points, or 0.37%, at 1791.53.
The Nasdaq Composite Index was also up 0.2% to 3993, within striking distance of 4000, in early trading but closed 36.90 points down, a fall of 0.93%.
This year’s rally has been driven by a combination of slow-but-steady economic improvement in the US and elsewhere and the US Federal Reserve's continued easy-money policies.
The Fed is buying $US85 billion worth of bonds each month and doesn’t look like “tapering” off any time soon
The Fed surprised investors when it decided against scaling back bond purchases in September. And last week, chairman-designate Janet Yellen defended the stimulus in remarks to Congress.
But the strength of the market has also led some to think the rally can continue even if the stimulus is withdrawn.