US STOCKS-Wall St falls on Fed concern after 8-week run higher

* Yum Brands (Munich: TGR.MU - news) ' November China sales flat, sending shares down

* Apple (NasdaqGS: AAPL - news) up after Topsy buy, UBS (Xetra: UB0BL6 - news) upgrade

* Cyber Monday sales appear strong

* Tesla's stock jumps

* Indexes down: Dow 0.7 pct, S&P 0.5 pct, Nasdaq 0.3 pct

By Caroline Valetkevitch

NEW YORK, Dec 3 (Reuters) - U.S. stocks fell on Tuesday, sending the S&P 500 index lower for three straight sessions, as investors speculated the Federal Reserve may move to trim its stimulus earlier than some had anticipated.

After eight weeks of gains in which the S&P 500 hit a series of record highs, investors may be locking in profits, analysts said.

Stronger-than-expected data on manufacturing and construction spending on Monday underscored views the Fed may soon begin scaling back its stimulus of $85 billion in monthly bond purchases.

While virtually all market participants accept the central bank will begin to trim the stimulus at some point, the timing remains in question. Many analysts still forecast the announcement will take place in March.

"In general, the idea of tapering and rising interest rates is still at the forefront," said Bryant Evans, portfolio manager at Cozad Asset Management in Champaign, Illinois.

The Fed has maintained it would begin to slow the program when certain economic measures meet its targets. This week's economic reports include November's payroll jobs on Friday.

Leading Tuesday's decline was the S&P consumer discretionary sector, which fell 1 percent.

One of the biggest percentage decliners was Yum Brands Inc , which lost 2.5 percent to $75.77 after it said November sales at established KFC restaurants in China, its top market, failed to grow despite a successful promotion. It forecast a return to earnings per share growth in 2014.

The Dow Jones industrial average was down 112.55 points, or 0.70 percent, at 15,896.22. The Standard & Poor's 500 Index was down 8.21 points, or 0.46 percent, at 1,792.69. The Nasdaq Composite Index was down 11.98 points, or 0.30 percent, at 4,033.28.

After a disappointing to start to the holiday shopping season, U.S. online sales are expected to hit $2 billion on "Cyber Monday," the highest since the data firm comScore began tracking such information. Still, shares of Amazon.com Inc slipped 2.1 percent to $383.96. The S&P retail index shed 1 percent.

"We've seen decent, but not great, spending at retailers at the start of the Christmas season," Evans said. But, he said, "online buying is flattening out the impact of the start of the season."

Apple Inc has acquired social media search and analytics company Topsy, which specializes in analyzing Twitter (Berlin: TWR.BE - news) data. UBS upgraded the iPhone maker to "buy." Apple (TLO: AP-U.TI - news) shares were up 2 percent to $562.18, giving the biggest boost to both the S&P 500 and Nasdaq 100 indexes.

Tesla Motors (Xetra: A1CX3T - news) ' stock jumped 12 percent to $139.13 in high volume and was the biggest daily percentage gainer on the Nasdaq after Morgan Stanley (Xetra: DWD.DE - news) named it a "top pick." Germany's motor transport authority said on Monday it planned "no further measures" after reviewing fires in Tesla cars in the United States and Mexico.

OncoMed Pharmaceuticals Inc (NasdaqGS: OMED - news) shot up 93 percent to $27 after the company said Celgene Corp (Munich: CG3.MU - news) would develop and market six of its anti-cancer stem cell experimental drugs for an upfront payment of $155 million. Celgene shares dipped 1 percent to $161.41.