* Retail sales drop more than expected in September
* S&P 500, Nasdaq at risk of turning negative for the year
* Indexes off: Dow 1.8 pct, S&P 1.7 pct, Nasdaq 1.3 pct (Updates to afternoon trading, changes byline)
By Caroline Valetkevitch
NEW YORK, Oct 15 (Reuters) - U.S. stocks were down more than 1 percent in afternoon trading on Wednesday as economic data added to worries over the health of the world economy and concern increased about the spread of Ebola.
But each of the three major indexes were well off their lows of the session. The S&P 500 had been down more than 3 percent earlier in the day.
Still, the losses threatened to wipe out 2014 gains for the S&P 500 and Nasdaq, while the Dow industrials fell further into the red for the year.
Concern over plunging oil prices, the potential impact of global economic weakness on U.S. earnings and the spread of Ebola have rattled markets. The S&P 500 was on track for its sixth fall in eight sessions and is down roughly 8 percent from its Sept. 18 record closing high.
The CBOE Volatility index, Wall Street's fear index, was last up 19.9 percent at 27.33 after earlier hitting its highest level since November 2011.
Worries about a lethargic global economy were not helped by data that showed U.S. retail sales and producer prices fell in September, while manufacturing activity in New York slowed to its weakest pace since April.
The pace and depth of the selloff have taken many investors by surprise, while others had been anticipating a pullback.
"It's normal and it's long overdue - markets can't grind higher for that long without some sort of get-back here," said Scott Armiger, portfolio manager at Christiana Trust in Greenville, Delaware.
The Dow Jones industrial average fell 294.67 points, or 1.81 percent, to 16,020.52, the S&P 500 lost 31.29 points, or 1.67 percent, to 1,846.41 and the Nasdaq Composite dropped 52.92 points, or 1.25 percent, to 4,174.25. (Additional reporting by Yasmeen Abutaleb; Editing by Nick Zieminski)