The Dow was down 0.53 per cent to 26,807.77, the S&P 500 decreased 0.84 per cent to 2,966.60, and the Nasdaq fell 1.46 per cent to 7,993.63.
At midday, the Dow Jones Industrial Average fell 21.42 points, or 0.08 per cent, to 26,928.57. The S&P 500 decreased 6.60 points, or 0.22 per cent, to 2,985.18. The Nasdaq Composite Index dropped 57.03 points, or 0.70 per cent, to 8,055.43, Xinhua news agency reported on Tuesday.
The majority of 30 blue-chip stocks in the Dow traded lower around midday, with shares of Goldman Sachs down over 2 per cent, leading the losers.
Shares of Apple turned red during midday, despite that US financial services company Jefferies upgraded Apple to "buy" from "hold," saying that Wall Street "underestimates the benefit Apple gets" from its opportunity in services in a note to clients on Tuesday.
Eight of the 11 primary S&P 500 sectors traded lower around midday, with the energy sector down nearly 1.2 per cent, leading the losers.
On the economic front, US consumer confidence index weakened to 125.1 in September, a sharp fall from August's 134.2, New York-based business research group the Conference Board said Tuesday.
The Present Situation Index - based on consumers' assessment of current business and labour market conditions - decreased from 176.0 to 169.0. The Expectations Index - based on consumers' short-term outlook for income, business and labour market conditions - declined from 106.4 last month to 95.8 this month.
"The escalation in trade and tariff tensions in late August appears to have rattled consumers," said Lynn Franco, senior director of economic indicators at the group, in a statement.
"While confidence could continue hovering around current levels for months to come, at some point this continued uncertainty will begin to diminish consumers' confidence in the expansion," Franco noted.
( With inputs from IANS )