The government shutdown heads into day 7, with some 350,000 workers back on the job. And a looming debt ceiling crisis is stoking fears of a possible U.S. default.
U.S. stock futures were sharply lower Monday, led by a nearly 1% decline in the S&P 500, and the dollar weakened against other global currencies.
With the deadline to raise the debt limit a little more than a week away, lawmakers appeared no closer to resolving the debt impasse over the weekend.
On Sunday, Treasury Secretary Jack Lew said that Congress was "playing with fire," and warned the U.S. could default in just over a week.
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That could lead to a "subsequent meltdown of global asset prices," said ETX Capital market strategist Ishaq Siddiqi.
U.S. stocks finished higher Friday, but the Dow declined 185 points, or 1.2%, for the week.
The wrangling in Washington is expected to dominate markets, in what is otherwise a light day for corporate and economic news.
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The first corporate results of the third quarter come out Tuesday, when aluminum maker Alcoa (AA) reports after the market close. Two of the biggest banks -- Dow component JPMorgan Chase (JPM)and Wells Fargo (WFC) report Friday morning.
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European markets fell in afternoon trading. The DAX in Frankfurt was under the most pressure, declining by more than 1%.
Asian markets ended with losses. Japan's Nikkei took a 1.2% tumble.