Copper futures suddenly plunged 6.3 percent to $5,489 a tonne as major chart support cracked. The industrial metal is often considered a weathervane of world demand.
Not helping the mood was news that the World Bank had cut its 2015 global growth forecasts to 3 percent from 3.4 percent because of sluggishness in the euro zone, Japan and some major emerging economies.
"The global economy is at a disconcerting juncture," World Bank chief economist Kaushik Basu told reporters. "It is as challenging a moment as it gets for economic forecasting."
That was a challenging background for equities, with MSCI's broadest index of Asia-Pacific shares outside Japan struggling to stay in the black and Australia's main share index slipping 0.3 percent.
Seeking to support growth, Japanese Prime Minister Shinzo Abe's cabinet approved a record $812 billion budget while cutting new borrowing for a third straight year.
The share market seemed underwhelmed, however, and the Nikkei lost 0.8 percent.
Wall Street ended on Tuesday with minor losses, led by a drop in materials and energy shares. It was a choppy session with the S&P 500 swinging from a gain of 1.4 percent to a fall of 1 percent before steadying.
The Dow eased 0.15 percent, while the S&P 500 dipped 0.26 percent and the Nasdaq 0.07 percent.
The dollar outpaced the euro on the back of upbeat U.S. economic data and after two European Central Bank (ECB) officials fuelled expectations that the bank would launch a program at its Jan. 22 policy meeting to buy government bonds.
The common currency fell as far as $1.1753 to reach a low not seen since December 2005. It last traded at $1.1769. Against the yen, the euro slumped to its lowest in over two months near 138.30.
Market attention now turns to the European Court of Justice (ECJ), which is expected to provide a non-binding opinion on the legality of an ECB bond-buying program later on Wednesday.
MONEY FOR NOTHING
The pressure for policy action has grown intense as falling oil prices pulled consumer prices into negative territory across the euro zone last month.
So far this week, Brent has lost 7 percent and U.S. crude 5 percent. On Wednesday, Brent gave up early gains and fell 25 cents to $46.34 per barrel, while U.S. crude shed 20 cents to $45.69.
The impact was clear in the UK where inflation halved to just 0.5 percent in December, the lowest in over 14 years. That only reinforced market expectations the Bank of England would not be able to hike rates until 2016 at the earliest.
Likewise, investors are wagering the Federal Reserve will find it hard to start tightening in the middle of the year, as some policy members have suggested.
In just the past three weeks, Fed fund futures have priced out 25 basis points of hikes for this year and now see just one move to 0.5 percent by Christmas.
The risk of low inflation for longer has in turn pulled down bond yields globally, with five-year debt in Germany and Japan now paying nothing at all.
One side effect of plunging bond yields is to make gold more attractive as an alternative investment.
Since gold does not pay a return, an opportunity cost for holding it is the yield forgone on safe-haven bonds. Now, that cost has diminished to the point where buying gold offers the same return as lending money to Germany for five years.
The yellow metal was was a shade softer at $1,230.00 an ounce on Wednesday after touching a three-month peak.
(Copyright Thomson Reuters 2015)