* World stocks tumble towards worst week of the year
* Apple weighs the most on the Nasdaq, S&P
* Eight of the 10 major S&P sectors in the red for the year
* Deere falls after reporting drop in profit
* Indexes down: Dow 1.73 pct, S&P 1.81 pct, Nasdaq 2.19 pct (Adds details, changes comment, updates prices)
By Tanya Agrawal
Aug 21 (Reuters) - The rout in U.S. stocks continued for the fourth straight day on Friday, with all three major indices down more than 1 percent, as fears of a China-led global slowdown were heightened after grim data overnight.
The Dow Jones industrial average and the S&P were poised for their sharpest weekly fall since November 2011. The Nasdaq was on track for its steepest weekly fall since August 2011. The Russell 2000 entered correction territory.
The selloff was broad based as all 10 major S&P sectors were in the red, led by the consumer discretionary sector. Eight of the 10 sectors were down more than 1 percent.
The CBOE Volatility index, a measure of the premium traders are willing to pay for protection against a drop in the S&P 500, jumped as much as 18.6 percent to 22.71, a more than six-month high. The index also notched its biggest weekly gain for the year.
Apple fell 3.2 percent to $109 as investors continued to fret over its prospects in China, a key growth market for the iPhone maker. The stock was the biggest drag on the S&P and the Nasdaq.
Data from China showed its giant manufacturing sector shrank at the fastest pace since 2009, exacerbating worries about its health. The data comes on the heels of weaker-than-expected economic data in July, the yuan's devaluation this month and a stock market plunge.
World stock markets tumbled towards their worst week of the year on Friday and commodities had another bruising day.
"China is the main concern. It looks like all of a sudden the market has latched on it," said Scott Wren, senior global equity strategist at Wells Fargo Investment Institute in St. Louis.
"You have to put this week's move into perspective. We are about 5 percent off from record highs and the market hasn't seen a 10 percent correction since the last three years. We still think there is potential for more downside, but view this as a buying opportunity."
At 11:13 a.m. ET (1513 GMT) the Dow Jones industrial average was down 294.67 points, or 1.73 percent, at 16,696.02.
The S&P 500 was down 36.78 points, or 1.81 percent, at 1,998.95 and the Nasdaq composite was down 106.86 points, or 2.19 percent, at 4,770.63.
The consumer discretionary index fell 1.55 percent. The consumer staples sector's 1.17 percent decline pulled the index into the red for the year. Now eight of the 10 sectors are negative for the year.
One of the few bright spots of the day was HP, which rose 4.9 percent to $28.70, rebounding from a 1-1/2 year low earlier, after brokerages including Citi Research and JP Morgan Securities reiterated their bullish stance on the stock.
The S&P 500 and the Dow closed in the red for the year on Thursday on concerns that the decelerating Chinese economy would translate into slower global growth.
Those fears and a U.S. inflation rate below the expected target has caused some investors to scale back bets that the Federal Reserve will raise interest rates in September.
"The movement in stocks, the correction in the last two days alone has served as a signal to people that maybe we should pay greater attention to the slowdown in emerging markets, commodity weakness and to the fact that crude's went from $100 to $40 in a year," said Brian Fenske, head of sales trading at ITG in New York.
Netflix fell 5.6 percent to $106.30 as the weakness in media stocks from Thursday looked set to continued.
Deere fell 7 percent to $84.32 after the maker of John Deere tractors, reported a 40 percent fall in quarterly profit.
Declining issues outnumbered advancers on the NYSE by 2,520 to 423. On the Nasdaq, 2,083 issues fell and 599 advanced.
The S&P 500 index showed no new 52-week highs and 61 new lows, while the Nasdaq recorded 6 new highs and 231 new lows. (Additional reporting by Sinead Carew; Editing by Savio D'Souza)