NEW YORK -- U.S. stocks fell on Wednesday on continued worries about weak global demand, but managed to close well above session lows that briefly pushed the S&P 500 and Nasdaq into negative territory for the year.

Small-caps and energy shares, which have been among the market's weakest performers, provided some of the late-day support, with the index <.TOY> ending up 1 percent and the index <.SPNY> up 0.4 percent.

Adding to the day's worries, a second nurse in tested positive for the Ebola virus, a week after , the first Ebola patient diagnosed in the , died.

The day's losses threatened to wipe out 2014 gains for the S&P 500 and Nasdaq, with the S&P 500 down more than 3 percent at its low. The Dow industrials fell further into the red for the year, down for the fifth consecutive session.

The S&P 500 is now down 7.4 percent from its Sept. 18 record closing high, and is up just 0.8 percent for the year.

"If you look at the lows of the day, maybe we've put in a little bit of a trading bottom here. But I don't think it makes these concerns about aggregate demand and inflation go away ... that's really what's weakening the market," said , chief market strategist at Ameriprise Financial in .

The Dow Jones industrial average fell 173.45 points, or 1.06 percent, to 16,141.74, the S&P 500 lost 15.21 points, or 0.81 percent, to 1,862.49 and the dropped 11.85 points, or 0.28 percent, to 4,215.32.

"There wasn't a single trigger," said Andre Bakhos, managing director at Janlyn Capital LLC in , .J. "We've been in a downtrend recently and it's been a continuation of the recent trend change to the negative."

A fall in 's inflation rate to a five-year low and a decline in U.S. producer prices for the first time in over a year were worrisome signs to investors already skittish about the path of the global economy and caused them to reassess their views on when the U.S. Federal Reserve might hike interest rates.

The latest news on the spread of added to a climate of fear, with another healthcare worker testing positive for the deadly virus, officials said Wednesday. Almost 4,500 people have died of the disease, mostly in West Africa.

An MSCI gauge of stocks in major markets was down 2.2 percent, its largest daily decline since June 2013. The Index rose to 29.54, after earlier hitting 31.06, the highest level since May 2011. Trading volume in the options market was projected to be its busiest on the year, according to Trade Alert data.

STOCKS FALL, BONDS RALLY

Worries about slammed airline stocks. The U.S. Centers for Disease Control and Prevention said the second nurse who was diagnosed with the virus had been on a plane the day prior.

Flight from risk resulted in a massive rally in U.S. Treasuries, pushing the 10-year note's yield as low as 1.865 percent, its lowest level since May 2013. Rate futures now show the market does not expect the Fed to raise rates until early 2016, a dramatic change from a few weeks ago.

The U.S. benchmark yield ticked above 2 percent in afternoon trading and 10-year Bund yields hit a record low of 0.719 percent before edging up to 0.757 percent.

"Everyone's animal spirit is dead. This is a pretty dramatic move when everyone was expecting higher rates," said George Goncalves, head of U.S. interest rates strategy at Nomura Securities International in New York. "It's all about capital preservation at this point. All the crowded trades are being tested, which is why I'm not sure this is over."

The spread of high-yield corporate bond spreads over the benchmark U.S. Treasuries, which represents the premium paid to investors to compensate for the risky corporate debt, rose to match the high hit in September 2013, at 483 basis points. The spread had bottomed at 335 bps in June.

A repricing of Fed expectations fueled a selloff in the dollar, which has been rising recently on bets on policy tightening at the Fed while other central banks continue easing.

"Some of the concerns about and the other economies slowing down has reached our shores today with the retail sales number and the PPI number," said , portfolio manager at in Greenville, .

Although U.S. September retail sales had been expected to decline, the weakness was surprising because it was broadbased.

The euro was last up 0.8 percent against the dollar at $1.2754, just below a three-week high of $1.2885 hit earlier. The greenback lost 0.7 percent against the yen at 106.27.

Spot gold prices rose 1.1 percent, up for the sixth time in the last eight sessions with the help of the weaker dollar, but copper prices tumbled 2.5 percent.

THE CRUDE TRAMPLING

Brent and U.S. crude futures fell, a day after posting their biggest daily drop in years, with more production, less demand and deflation expectations weighing heavily.

Brent lost 0.8 percent to $84.35 a barrel while U.S. crude fell 0.7 percent to $81.26.

Emerging markets were also hit with a fall in 's rouble to its weakest level on record, while Russian government 10-year yields hovered near a five-year high and shares in closed near a seven-month low hit last week.