US STOCKS-Wall St dips in volatile trade; oil prices fall further
* Energy sector lower; banks, utilities big losers
* Petsmart to be acquired by private equity consortium
* Indexes off: Dow 0.3 pct, S&P 0.3 pct, Nasdaq 0.7 pct (Updates to afternoon, changes byline)
By Caroline Valetkevitch
NEW YORK, Dec 15 (Reuters) - U.S. stocks were down slightly in volatile trading on Monday afternoon as investors assessed the impact of another big drop in oil prices.
U.S. crude fell 3.3 percent to settled at $55.91, hitting fresh 5-1/2 year lows. Both U.S. crude and Brent have fallen nearly 50 percent from highs in June.
The S&P 500 energy index bounced between positive and negative territory and was last down 0.5 percent, while financials and utilities were among the biggest negatives.
"What continues to be the focus for the markets is oil," said Tim Ghriskey, chief investment officer of Solaris Group in Bedford Hills, New York.
"There was some buying, and we'll see evidence of this ... buying on the dips." Continuación...