* Apple biggest drag on S&P, Nasdaq
* Exxon, Chevron fall on lower crude prices
* Valeant slumps as CEO goes on medical leave
* Disney up as latest Star Wars rakes in $1 bln
* Indexes down: Dow 0.60 pct, S&P 0.73 pct, Nasdaq 0.88 pct (Adds details, changes comment, updates prices)
By Abhiram Nandakumar
Dec 28 (Reuters) - Wall Street began the last trading week of the year in the red, dragged down by energy stocks, as oil prices resumed a slide brought on by global oversupply.
The 1.97 percent fall in the energy sector was the worst performance on the S&P 500. Exxon's shares were down 1 percent at $78.57, while Chevron was down 1.9 percent at $90.34. The stocks were among the biggest drags on the S&P and the Dow.
"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.
All three major indexes posted their best weeks since mid-November last week, rising about 2.5 percent, led by a short-lived surge in energy stocks.
The S&P 500 slipped back into negative territory for the year on Monday, down 0.6 percent, while the Dow was down 2.1 percent. The Nasdaq Composite was up 5.7 percent.
At 11:05 a.m. ET (1605 GMT), the Dow Jones industrial average was down 105.53 points, or 0.6 percent, at 17,446.64, the S&P 500 was down 15.02 points, or 0.73 percent, at 2,045.97 and the Nasdaq Composite index was down 44.28 points, or 0.88 percent, at 5,004.21.
Apple was down 1.5 percent at $106.44 and was the biggest drag on the S&P and Nasdaq. Goldman Sachs' 1.3 percent decline weighed the most on the Dow.
Trading volumes are expected be subdued through the week, which is likely to exacerbate volatility.
Valeant was down 9.7 percent at $103.09 after the Canadian drugmaker said Chief Executive Michael Pearson is going on medical leave.
Fitbit was up 2.9 percent at $29.74, after reports that the wearable gadget maker's iOS app was the most downloaded after Christmas, suggesting strong holiday demand.
Dow component Disney was up 0.9 percent at $106.83, after the company's latest Star Wars installment topped $1 billion in ticket sales.
Declining issues outnumbered advancing ones on the NYSE by 2,336 to 605. On the Nasdaq, 1,922 issues fell and 740 advanced.
The S&P 500 index showed no new 52-week highs and no new lows, while the Nasdaq recorded 22 new highs and 24 new lows. (Reporting by Abhiram Nandakumar in Bengaluru; Editing by Don Sebastian)