US STOCKS-Wall St. falls as oil's multi-year low adds to investor fears
* Oil plunges to seven-year lows
* Fed to decide on interest rate hike next week
* Volatility index at its highest since early October
* DuPont, Dow Chemical fall after agreeing to merge
* Indexes down: Dow 1.8 pct, S&P 1.9 pct, Nasdaq 2.2 pct (Updates to late afternoon, adds commentary)
By Marcus E. Howard
Dec 11 (Reuters) - U.S. stocks closed sharply lower on Friday, with the S&P 500 ending its worst week since August, as plunging crude oil prices compounded investor nervousness on expectations for the first U.S. interest rate hike in nearly a decade.
Oil dragged down market as a whole, as investors worried whether a weakness in commodities signaled a broader slowdown.
Furthermore, investors were worried about declines in China's yuan and in high-yield debt markets. Continuación...