The S&P 500 was on track for a sixth day of losses as weak forecasts from chipmakers added to concerns about the impact on earnings from tariffs and a slowdown in China's economy.
A flight to safety boosted the dollar index, which rose 0.54 percent against a basket of six rival currencies to 96.438 . The Japanese yen, another safe-haven currency often bought when broader markets slide, strengthened over the day to 112.23, up 2 percent from a trough on Oct. 4.
Euro zone business growth slowed more than expected this month, a widely watched Purchasing Managers Index (PMI) survey showed. German private-sector growth fell to its lowest in more than three years, and manufacturing in France hit a 25-month low, according to other surveys.
Against the dollar, the euro fell as much as 0.8 percent, breaking below the technically significant level of $1.14. It was last at $1.139 and headed towards its biggest daily loss since Sept 27.
The European reports "came in weaker than expected and suggest that some of the softness we saw in Q2 and Q3 may not be as temporary as people were assuming," said Daniel Katzive, head of foreign exchange strategy for North American at BNP Paribas.
"Even though the US is starting to show some cracks and vulnerability to global trade and geopolitical stresses, Europe is still more vulnerable from an economic perspective."
The European Central Bank holds its monetary policy meeting on Thursday, and investors will be looking for any comments about the deepening row between the European Union and Italy over Rome's budget.
The British pound hit a six-week low of $1.287 earlier in the day as markets awaited the outcome of Prime Minister Theresa May's meeting with Parliament after talk of a leadership challenge over her Brexit strategy.
May received a show of support from her Conservative Party on Wednesday, which lifted the pound modestly but left it down 0.77 percent over the day. It was last at $1.288.
The Canadian dollar fell by as much as 0.91 percent on Wednesday morning after the country's central bank raised interest rates as expected and said more hikes would be needed to keep inflation in check. The loonie had retraced some of its losses in the afternoon session, and was last at $1.302.