* Twitter slumps after results
* Green Mountain surges on deal with Coca-Cola
* Initial claims decline more than expected
* Retailers report monthly sales
* Futures up: Dow 42 pts, S&P 4.5 pts, Nasdaq 12.25 pts
NEW YORK, Feb 6 (Reuters) - U.S. stocks were set for a slightly higher open on Thursday, as a better-than-expected report on weekly initial jobless claims boosted confidence the economy was improving, although caution remained ahead of Friday's employment report.
* The number of Americans filing new claims for unemployment declined 20,000 to a seasonally adjusted 331,000, versus expectations of 335,000 claims. The prior week was revised to show 3,000 more applications received than previously reported while the four-week moving average nudged up 250 to 334,000.
* As the U.S. Federal Reserve continues efforts to wind down its stimulus, investors have turned their focus to fundamentals such as corporate earnings and economic data.
* However, many participants have wondered if recent soft data truly reflects the economy or is the result of a harsh winter, and are looking to Friday's payrolls report for a clearer indication of the economy's health after last month's disappointing number.
* Twitter Inc shares tumbled 22.4 percent to $51.20 in premarket trade. After the close on Wednesday, the company reported its slowest pace of user growth in recent company history, dimming hopes that the social media phenomenon could sustain its torrid pace of expansion.
* Green Mountain Coffee Roasters Inc surged 40.6 percent to $113.70 before the opening bell. Coca-Cola Co had bought a 10 percent stake in it for $1.25 billion and would help launch Green Mountain's new cold drink machine planned for release as soon as October. Coke shares gained 1.7 percent to $38.23 while home beverage device maker SodaStream International reversed course after an earlier decline and rose 10.5 percent to $39.56 in premarket trading.
* S&P 500 e-mini futures rose 4.5 points and were slightly above fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures gained 42 points and Nasdaq 100 futures added 12.25 points.
* Other economic data showed the U.S. trade deficit widened more than expected in December as exports fell, which could see the advance fourth-quarter growth estimate trimmed. Nonfarm productivity rose more than expected in the fourth quarter, but weak unit labor costs pointed to subdued wage inflation.
* The European Central Bank left interest rates unchanged on Thursday, holding off policy action while it waits for new economic forecasts next month to assess the deflation threat facing the euro zone.
* Investors will eye monthly sales results from retailers for signs of strength in consumer spending. Costco Wholesale Corp's January same-store sales beat market expectations, even as the warehouse club retailer recorded weak fuel prices and lower international sales in dollar terms.
General Motors lost 4 percent to $33.82 before the opening bell after the automaker posted weaker-than-expected fourth-quarter profit on Thursday as results in North America, Asia and South America disappointed.
* Dunkin' Brands Group Inc reported a 23 percent rise in quarterly profit, driven by higher growth in sales at its Dunkin' Donuts coffee and sandwich outlets. The company also boosted its quarterly dividend and announced a new $125 million share buyback plan. Its shares rose 2.1 percent to $48.31 in premarket.
* Aetna Inc, the third-largest U.S. health insurer, on Thursday said fourth-quarter profit rose due to the acquisition of Coventry Healthcare, and it forecast an increase in medical customers in its private Medicare business in 2014.