Craigs Investment Partners broker Chris Timms said doubts were mounting on whether the administration of US President Donald Trump could deliver on its pro-business policies.
Government bonds and gold strengthened, while the US dollar fell as some investors said political uncertainty was deflating a post-election rally that pushed the Dow to record highs earlier.
''There's some disappointment about the administration's failure on health care and what that might mean for the rest of their agenda,'' he said.
On Friday afternoon, House Republican leaders abandoned a bill to repeal Obamacare amid a lack of support, raising doubts about the likely success of other complex legislative efforts, including a tax overhaul and infrastructure spending.
If the Dow closes lower today, it would mark the eighth straight declining session.
The last time the blue-chip index fell for eight consecutive days was in late July and early August 2011, when the debt-ceiling standoff prompted fears of a default by the US government.
Financial shares were the biggest ones to fall in the S&P 500, falling 0.9%.
