U.S. stocks suffered their worst day in seven weeks as equities around the world took a dive Wednesday and commodities tumbled.

Oil and metal futures fell sharply and the dollar faded after hitting a 13-month high earlier in the day.

Turkey's lira gained for a second day against the dollar, rising 7 percent on Wednesday after authorities took action against investors aiming to short the currency.

The euro also regained ground after news Qatar pledged to invest $15 billion in Turkey, reducing anxiety about European banks' exposure.

The dollar index fell 0.03 percent, with the euro up 0.04 percent to $1.1346.

China was in sharp focus as the yuan sagged nearly 0.8 percent to 6.9514 per dollar, hitting its weakest level since January 2017.

An unexpected drop in profits for Chinese tech giant Tencent surprised investors and added to some recent concerns about the health of China's economy. Tencent, a gaming and messaging company, and it's the most valuable technology company in China.

Earlier this week, reports on growth in factory output, consumer spending and retail sales in China were all slower than expected.

Large technology companies including Alibaba and Baidu of China and U.S. tech giants including Facebook and Microsoft fell.

MSCI's emerging equities index fell 1.8 percent after having dropped more than 20 percent from its January intraday high earlier in the day. Latin American currencies also slid.

The S&P 1500 Metals & Mining index fell 4.8 percent, in its biggest one-day percentage decline since March.

Spot gold dropped 1.6 percent to $1,174.58 an ounce.

Copper lost 4.02 percent to $5,801.00 a ton and zinc fell 6.3 percent and touched its lowest level since October 2016.

"Copper and other commodities at first reflected the downturn in China but now have been exacerbated by expectations of further economic weakness," said Kristina Hooper, chief global market strategist at Invesco in New York.

The Dow Jones industrial average fell 137.51 points, or 0.54 percent, to 25,162.41, the Standard & Poor's 500 index lost 21.59 points, or 0.76 percent, to 2,818.37 and the Nasdaq composite dropped 96.78 points, or 1.23 percent, to 7,774.12.

The pan-European FTSEurofirst 300 index lost 1.41 percent and MSCI's gauge of stocks across the globe shed 1.10 percent.

The CBOE Volatility Index, Wall Street's so-called "fear gauge," added 1.33 points to 14.64 after jumping to a more than six-week high of 16.86 earlier in the session.

Benchmark 10-year U.S. Treasury notes last rose 9/32 in price to yield 2.8641 percent, from 2.895 percent late Tuesday.

The backdrop to all this is the escalation in global trade tensions, with Beijing lodging a complaint to the World Trade Organization to determine the legality of U.S. tariff and subsidy policies.

Turkey has also raised tariffs on some U.S. products "in response to the U.S. administration's deliberate attacks on our economy," Vice President Fuat Oktay wrote on Twitter.

U.S. crude oil fell 3.18 percent to $64.91 per barrel and Brent was last at $70.75, down 2.36 percent on the day after data showed a surprise weekly increase in U.S. crude stockpiles, compounding worries about a weaker global economic growth outlook.