US STOCKS- Dow, S&P 500 end up in late turnaround; Alcoa dips after hours
* Oil prices fall; U.S. crude settles down 5.3 pct
* Freeport drops; China worries weigh on materials shares
* McKesson, Celgene slump on weak profit forecasts
* Indexes: Dow up 0.3 pct, S&P up 0.1 pct, Nasdaq down 0.1 pct (Updates close with Alcoa down slightly after the bell and with latest volume)
By Caroline Valetkevitch
Jan 11 (Reuters) - The Dow and S&P 500 ended a volatile session up slightly on Monday in a late turnaround, but a drop in biotechs and energy shares kept a lid on the market.
The start of earnings season added to investor nervousness. The Nasdaq ended lower, led by a drop in biotech company Celgene , which fell 5.5 percent to $103.03 following a disappointing profit forecast.
The Nasdaq Biotech index fell 3.4 percent in its eighth straight down day.
Stocks had their worst five-day start to a year ever following mounting investor concerns about declining oil prices and a China-led slowdown in global growth. Continuación...