US STOCKS-Wall St dips, data gives muddled picture before Fed

* Jobless claims fall more than expected, but data skewed

* Export prices fall for 6th straight month

* Indexes off: Dow 0.1 pct, S&P 0.3 pct, Nasdaq 0.1 pct

By Rodrigo Campos

NEW YORK, Sept 12 (Reuters) - U.S. stocks fell in light volume on Thursday, snapping seven straight gains by the S&P 500 index, as an incomplete report on the U.S. jobs market left traders with little to guide them about next week's Federal Reserve meeting.

First (Other OTC: FSTC - news) -time weekly claims for state unemployment benefits, the last major reading on the labor market before the Fed's meeting, fell to the lowest level since 2006, but the picture was confused because two states did not process all their claims.

The S&P 500 has risen 3.4 percent over the prior seven sessions, its longest winning streak in two months, as concerns about a Western military strike against Syria have faded.

Investors are looking ahead to the Fed's meeting on Tuesday and Wednesday and a news conference when a decision is expected about whether to change its $85 billion-a-month purchases of Treasury and mortgage bonds stimulus.

Economists at a majority of U.S. primary dealers expect the Fed to announce it will cut its bond purchases, according to a recent Reuters poll.

"The market understands there's been a correlation between (Fed stimulus) programs and the direction of equity prices," said Nicholas Colas, chief market strategist at the ConvergEx Group in New York.

"If they cut by more than $10 billion or $15 billion, the initial reaction will be negative," Colas (Stuttgart: 853381 - news) , who expects a reduction of $10 billion in purchases of Treasuries, added.

But it will also indicate the Fed sees the economy in better standing than most think, he said.

Spot gold prices fell nearly 4 percent ahead of the Fed meeting. Materials shares led the decline on the S&P 500, with gold miner Newmont Mining off 3.3 percent at $28.48.

The Dow Jones industrial average fell 21.42 points or 0.14 percent, to 15,305.18, the S&P 500 lost 4.81 points or 0.28 percent, to 1,684.32 and the Nasdaq Composite dropped 4.415 points or 0.12 percent, to 3,720.595.

U.S. Secretary of State John Kerry flew to Geneva on Thursday to hear Russia's plans to disarm Syria of its chemical weapons and avert U.S.-led military strikes, an initiative that has transformed diplomacy in the two-and-a-half-year-old civil war.

"Russia has emerged as such a vocal counterpoint to U.S. policy in Syria it makes you think inaction is probably the order of the day, the week, and probably the month," said Colas. "It makes you think nothing's going to happen, at least in a military level."

ANOTHER INDEX SHUFFLE

A day after announcing its largest change to the Dow Jones (DJI: ^DJI - news) industrials in nearly a decade, S&P Dow Jones Indices announced late Wednesday that Vertex Pharmaceuticals Inc and Ametek Inc (NYSE: AME - news) will replace Advanced Micro Devices Inc (NYSE: AMD - news) and SAIC Inc (NYSE: SAI - news) in the S&P 500 after the close of trading on Sept. 20.

Vertex shares gained 1.3 percent to $80.87 and Ametek rose 2.2 percent to $45.40. AMD fell 1.8 percent to $3.75 and SAIC edged up 0.9 percent to $14.90.

Lululemon Athletica Inc (NasdaqGS: LULU - news) slumped 5.4 percent to $65.30 after the apparel retailer reported second-quarter results and trimmed its outlook.

NetSol Technologies Inc (NasdaqCM: NTWK - news) jumped 10.1 percent to $11.23 after the software maker reported fourth-quarter earnings.