Gold hit a near six-month high, as fears of more corporate defaults in China and the geopolitical tug-of-war in Ukraine hurt equity markets.
Concerns about China and other developing economies weakened the Australian dollar and currencies closely linked to commodities markets.
Stocks were little changed Wednesday, as the Dow and the S&P flirted with gains after two a two-day drop.
U.S. stock-index futures pointed to a higher open on Thursday.
Bonds rose in safe-haven bids on worries over the health of China's economy, which helped fuel strong demand at the government's 10-year note auction.
European stocks closed lower on Wednesday amid lingering worries over China's economy and concerns about tensions in Ukraine.
Crude was hurt by a large rise in U.S. oil inventories and a report that the government planned to release crude from its reserve.
Brent held near $108 a barrel as a worsening crisis over Ukraine stoked supply disruption fears.
The ECB's forward guidance may adjust policy to tighten the slack in the Euro zone economy, a senior ECB official said.
Ongoing worries over China's economy weighed Asian equity markets down on Wednesday, while overnight losses on Wall Street further ignited a flight-to-safety.
Stocks declined on Tuesday as news from China hit commodity prices..
U.S. stock index futures slumped on Wednesday, as shares in Europe and Asia fell on concerns about China's economy and the turmoil in Ukraine.
Government bonds were little changed after the US government's auction of three-year Treasury notes, the first of three debt auctions this week.
European stocks closed mixed on Tuesday as as the crisis in Ukraine curbed enthusiasm for riskier assets.
U.S. oil fell by more than $1 per barrel, pressured by a drop in China's exports that stoked slowdown fears.
Gold settled higher as fears of an economic slowdown in China and Ukraine's geopolitical crisis keep investors seeking safe-haven bullion.
Stocks staged a mixed finish Friday, with the S&P 500 not far from its record high.
Asian stocks overcame an uninspiring handover the U.S. to trade higher on Tuesday after posting steep declines in the previous session.
U.S. stock index futures pointed to a flat open on Tuesday, with stocks in Asia and Europe rebounding.
Stocks fell on Monday, a session after the S&P hit another all-time high.
Get the best of CNBC in your inbox