* Investors unsure of Fed's timing for tapering
* ADP employment report tops expectations
* Both OmniVision and Express shares slide after outlook
* Dow off 0.2 pct, S&P 500 down 0.1 pct, Nasdaq up 0.02 pct
By Ryan Vlastelica
NEW YORK, Dec 4 The Dow and the S&P 500 finished lower for the fourth consecutive session on Wednesday after investors found few reasons to make big moves, with uncertainty remaining over when the Federal Reserve will start to slow its stimulus.
Stocks fell for much of the session, but edged closer to break-even levels in the last hour of trading. Still, the losses were broad, with eight of the 10 S&P 500 sector indexes ending lower for the day on concerns that the market's recent rally to record levels was not justified.
About 60 percent of the shares traded on the New York Stock Exchange closed lower for the day, while 56 percent of Nasdaq-listed stocks closed down.
Many market participants expect the Fed to announce a cut in its $85 billion in monthly bond purchases in March, but recent economic data increased expectations that the move may come sooner. The Fed has said it would slow its stimulus program when certain economic measures meet its targets, including a decline in the U.S. unemployment rate.
The ADP National Employment Report showed private-sector employers added 215,000 jobs in November, more than expected. This was the latest in a string of reports suggesting that the economy's outlook was brightening.
"Stronger economics means earlier tapering, which is a negative for the market. On top of that, we've surged to new highs with a lot of optimism, and that normally calls for a pullback, if only briefly," said Bruce McCain, chief investment strategist at Key Private Bank in Cleveland, Ohio.
"If the decline is mostly about sentiment, we should work through it quickly and be back to seeing better action," he added. "But the pullback could be more pronounced, the more people focus on the Fed."
The Dow Jones industrial average slipped 24.85 points, or 0.16 percent, to end at 15,889.77. The Standard & Poor's 500 Index declined 2.34 points, or 0.13 percent, to finish at 1,792.81. But the Nasdaq Composite Index inched up just 0.80 of a point, or 0.02 percent, to close at 4,038.00.
In the Fed's Beige Book, a collection of anecdotes from the central bank's business contacts across the nation, the Fed said employers had stepped up hiring in some parts of the country in October and early November, and the economy had expanded at a "modest to moderate pace."
Other signs of strength in the economy were figures showing that the U.S. trade deficit narrowed in October and new home sales recorded their biggest increase in nearly 33-1/2 years in October. The home sales report suggested that the housing market's recovery remains intact despite higher mortgage rates. Shares of KB Home rose 1.1 percent to $17.26.
But the economic picture was muddied after the Institute for Supply Management said its services index fell to 53.9 last month from 55.4 in October. A forecast called for a November reading of 55.0. A figure above 50 signifies expansion.
U.S. crude oil futures prices advanced 1.2 percent, up for a fourth straight day as government data showed an unexpected drop in U.S. stockpiles. Crude is up 5.3 percent over the past four sessions.
Shares of Marathon Oil rose 1.4 percent to $36.74. The stock of Hess Corp added 1.3 percent to $82.21.
Among decliners, shares of clothing retailer Express Inc tumbled 23 percent to $19 after the company forecast quarterly earnings below analysts' estimates because of weaker-than-expected Thanksgiving sales.
OmniVision Technologies Inc slid 2.9 percent to $15.52 after the chipmaker forecast current-quarter revenue well below analysts' estimates.
After the market closed, Aeropostale Inc fell 3.6 percent to $9.01 following the release of its third-quarter results. The stock ended regular trading at $9.36, down 3.9 percent.
Oculus Innovative Sciences Inc shares surged 103.4 percent to $4.74 after the company got the go-ahead from the U.S. Food and Drug Administration for its anti-scar gel.
About 6.54 billion shares traded on all U.S. platforms, according to BATS exchange data.