YAHOO: On Wednesday, stocks tumbled 5.3%, ending at session lows in broad-based weakness. The decline was driven by profit taking, and discouraging economic data on employment and the services sector.  Meanwhile, investors digested Barack Obama winning the presidency and other election results.

According to the ADP national employment report, nonfarm private employment declined by 157,000 in October, which is the largest decline since 2002. The result was worse than the expected drop of 100,000. September was revised to a decrease of 26,000 from a decrease of 8,000. The ADP data have had a spotty track record compared to the government's report, which includes both public and private nonfarm payrolls, and is set for release on Friday.

The services sector contracted by the most since at least 1997 and the sixth time this year, according Institute for Supply Management's national nonmanufacturing survey, which dates back to 1997. Specifically, the October ISM Services Index registered 44.4 in October, 2.6 worse than expected and 5.8 lower than the 50.2 reading in September. A reading below 50 is intended to imply contraction in the services sector.

In corporate news, Google (GOOG 342.57, -24.37) announced on its blog that it decided to end its advertising agreement with Yahoo! (YHOO 13.93, +0.58) after it became clear that government regulators and some advertisers continued to have concern about the pact. Google traded down on the news, while Yahoo saw a boost as traders speculated this may open the door to another Microsoft (MSFT 22.07, -1.46) offer.

All ten of the economic sectors posted a loss.

Financials (-8.8%) were the main laggard.  A wider-than-expected quarterly losses from bond insurers Ambac (ABK 2.06, -1.34) and MBIA (MBI 8.31, -2.15) along with a disappointing earnings and outlook from REIT General Growth Properties (GGP 2.09, -2.40) added to selling interest.

The energy sector fell 4.6% as crude prices plunged 7.4% to $65.28 per barrel.  The drop in oil prices was fueled by economic concerns and weekly energy inventory data that showed the sixth increase in crude stockpiles and an increase in gasoline levels.

Quarterly earnings results were mixed, with outlooks leaning negative. Some notable companies that reported worse-than-expected earnings include  Arcelor Mittal (MT 25.16, -6.54), Duke Energy (DUK 15.61, -1.31), Marsh McLennan (MMC 26.07, -3.63), MBIA (MBI 8.31, -2.15), Molson Coors (TAP 41.87, +3.29) and Transocean (RIG 80.61, -3.91).

Devon Energy (DVN 79.64, -3.36), Medco Health Solutions (MHS 41.45, +3.45), Polo Ralph Lauren (RL 48.54, -0.97), Sara Lee (SLE 10.22, -1.64), and Time Warner (TWX 10.15, -0.68) beat in their latest quarters.

The S&P 500 is now down 1.7% this week, but is still up 13.5% from its Oct. 10 multi-year low.  It is down 37.5% this year.DJ30 -486.01 NASDAQ -98.48 NQ100 -5.7% R2K -5.7% SP400 -5.1% SP500 -52.98 NASDAQ Adv/Vol/Dec 534/2.18 bln/2232 NYSE Adv/Vol/Dec 603/1.31 bln/2490