US STOCKS-Wall Street loses ground as oil decline deepens
* Apple biggest drag on S&P, Nasdaq
* Exxon, Chevron fall as crude prices slide
* Valeant slumps as CEO goes on medical leave
* Disney up as latest Star Wars film rakes in $1 bln
* Indexes down: Dow 0.21 pct, S&P 0.34 pct, Nasdaq 0.39 pct (Updates to afternoon)
By Noel Randewich
Dec 28 (Reuters) - Wall Street fell on Monday, hurt by a steep drop oil prices as well as a dip in Apple shares, pushing the S&P 500 back into negative territory for 2015.
The S&P 500 energy sector lost 1.7 percent, easily the worst performer as a 3 percent drop in oil prices led investors to sell unload shares of Exxon Mobil, down 0.7 percent, and Chevron, which fell 1.68 percent.
"It's mostly on crude. That's more the issue than anything else," said Paul Nolte, senior vice president and portfolio manager at Kingsview Asset Management in Chicago. Continuación...