Stocks declined Tuesday amid increased conflict in the Middle East and as the U.S. moved to curb inversion deals.
U.S. bonds continued to gain on Tuesday, although two-year notes traded flat ahead of a Treasury auction.
European shares closed lower on Tuesday, due to weak economic data and new tax rules in the U.S. hitting the pharmaceutical sector.
Brent crude rose above $97 after a survey showed China's factory activity unexpectedly picked up in September, helping brighten the demand outlook.
Gold rose as the dollar eased after comments from a NY Fed official that any increase in interest rates should be done cautiously.
The battered euro pulled away from a 14-month trough against the dollar, as the greenback eased after a 10-week streak of gains.
Asian stocks ended mixed on Tuesday following Chinese factory data but trade was quiet with Japan shut for the Autumnal Equinox holiday.
Stocks fell Monday, retreating from record levels, as China signaled it would not boost stimulus.
Wall Street looked set to open lower again on Tuesday, after the U.S. announced it had launched airstrikes in Syria.
Long-dated Treasury yields dipped to their lowest in over a week on the view that weak U.S. data may force the Fed to be dovish on interest rates.
European shares closed down on Monday, with sentiment curbed by lower commodity prices as well as an profit warning from supermarket Tesco.
Gold prices edged up on short covering after a dollar rise and technical selling earlier sent the precious metal into its weakest since early January.
Brent crude fell below $98 a barrel on Monday as sluggish demand and abundant supplies outweighed a possible cut in oil output from the OPEC.
The dollar index racked up a 10th straight week of gains on Monday, its longest winning streak since its free float in 1973.
Asian markets started the data-light week on the back foot, with major indices posting steep losses.
Wall Street looked set to start the week lower, following the buzz around Alibaba's market debut and the Scottish referendum last week.
Stocks rose Friday amid enthusiasm for Alibaba's market debut and relief over voting in Scotland.
U.S. sovereign bonds fell on Friday, with the yield curve flattening, after Scotland voted again independence from the United Kingdom.
European shares closed higher after voters in Scotland rejected independence and opted to remain within the United Kingdom.
Gold settled nearly 1 percent lower on Friday, logging a third straight weekly drop, as the dollar rallied.
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