Retail sales dropped a seasonally adjusted 0.9% last month to mark the biggest decline in nearly a year.

NEW YORK (MarketWatch) — The U.S. dollar plummeted Wednesday morning after December retail sales were much weaker than expected.

The euro EURUSD, +0.29%  turned positive against the dollar after hitting a nine-year low early Wednesday. The shared currency trade at $ 1.1835, compared to $ 1.1738 before the data.

The ICE U.S. Dollar Index DXY, -0.26%  , a measure of the dollar’s strength against a trade-weighted basket of six rival currencies, was down 0.55% to 91.8000, erasing two sessions of gains.

The retail sales data cast doubt on the idea that falling gasoline prices would provide a helpful boost to the U.S. economy, said Rob Carnell, chief international economist at ING.

“With the US about the only beacon of growth globally, if even this engine is spluttering, then a more substantial market correction than we have already seen may well be on the cards,” Carnell said.

Retail sales dropped a seasonally adjusted 0.9% last month to mark the biggest decline in nearly a year, the Commerce Department said Wednesday. Economists polled by MarketWatch were expecting a 0.2% decline.

Excluding gas and car sales, retail sales were still down 0.3%, falling far short of Wall Street’s expectation for a 0.3% to 0.5% increase.

(Read: U.S. retail sales slump in December)

The dollar tumbled against the yen USDJPY, -0.95% falling to ¥116.1150, its lowest level since mid-November.

After trading flat against the dollar during the Asia and European trading days, the pound GBPUSD, +0.49%  rose to $ 1.5270, its highest level since Jan. 6.

Earlier, the euro hit another in a series of nine-year lows after the European Court of Justice ruled that the European Central Bank’s Outright Money Transactions program was consistent with European Union law, leaving the door open for full-scale quantitative easing. The shared currency also traded below the level it was launched at in 1999.

U.S. stocks tumbled out of the gate with the Dow Jones Industrial Average DJIA, -1.43%   sinking 211 points, or 1.17%, to 17405, while the S&P 500 SPX, -1.10%  was off nearly 20 points, or almost 1%, to 20002.9.