* Morgan Stanley leads weak results on Monday
* Exxon, Chevron drag down S&P 500, Dow
* Weight Watchers soars after Oprah takes stake
* China Q3 GDP data weighs on commodities
* Dow down 0.04 pct, S&P down 0.1 pct, Nasdaq up 0.2 pct (Updates to late afternoon)
By Caroline Valetkevitch
Oct 19 (Reuters) - Weak quarterly results from Morgan Stanley and sliding oil prices weighed on U.S. stocks in late trading Monday, offsetting a rebound in biotech shares.
The energy index fell 2.2 percent as U.S. crude oil fell 2.9 percent. Copper fell after data showing a slowdown in China's economic growth.
Exxon and Chevron fell 2 percent and were the biggest drags on the S&P 500 and on the Dow Jones industrial average.
Morgan Stanley's shares fell 5.5 percent to $32.09 after the bank's profit fell for the second straight quarter, capping mostly downbeat quarterly results from major U.S. banks. The stock recorded its biggest results-day decline since 2009.
"People are waiting for an onslaught of earnings," said Peter Tuz, president of Chase Investment Counsel in Charlottesville, Virginia.
"There's been enough negative guidance about the future to make people skeptical about the direction of the market."
Several Dow components are posting quarterly results this week, including Caterpillar, Boeing and Coca-Cola . S&P 500 earnings are expected to have declined about 4 percent in the third quarter from a year ago, according to Thomson Reuters data.
The Dow Jones industrial average fell 7.58 points, or 0.04 percent, to 17,208.39, the S&P 500 lost 2.11 points, or 0.1 percent, to 2,031 and the Nasdaq Composite added 10.65 points, or 0.22 percent, to 4,897.34.
The Nasdaq biotech index was up 0.8 percent.
China's economic growth slowed to 6.9 percent between July and September, but still ahead of the 6.8 percent forecast.
U.S. homebuilder sentiment improved in October, with the NAHB/Wells Fargo Housing Market index rising to 64, ahead of the 62 expected. An index of housing stocks was up 0.1 percent.
Halliburton fell 2.0 percent to $37.05 after reporting a bigger-than-expected drop in quarterly revenue.
Weight Watchers doubled in value to $13.97 after it said Oprah Winfrey will buy a 10-percent stake in the company and join its board.
Declining issues outnumbered advancing ones on the NYSE by 1,732 to 1,310, for a 1.32-to-1 ratio on the downside; on the Nasdaq, 1,462 issues fell and 1,286 advanced for a 1.14-to-1 ratio favoring decliners.
The S&P 500 posted 17 new 52-week highs and 3 lows; the Nasdaq recorded 47 new highs and 37 lows. (Additional reporting by Abhiram Nandakumar in Bengaluru; Editing by Don Sebastian and Nick Zieminski)