* China, German trade data signal growth in demand
* Narrower U.S. trade deficit should boost GDP
* Shares of LinkedIn surge on earnings, outlook
* Indexes up: Dow 0.4 pct; S&P 500 0.6 pct; Nasdaq 0.9 pct
NEW YORK, Feb 8 (Reuters) - The Nasdaq composite index closed at a 12-year high and the S&P 500 index at a five-year high as stronger U.S. and international trade data lifted stocks on optimism about the economy.
The S&P 500 also posted a sixth straight week of gains for the first time since August.
Data showed Chinese exports grew more than expected, while another report showed the U.S. trade deficit had narrowed in December, indicating the U.S. economy strengthened in the fourth quarter.
"That may have sent a ray of optimism," said Fred Dickson, chief market strategist at D.A. Davidson & Co in Lake Oswego, Oregon.
Trading volume on Friday was below average for the week as a blizzard swept into the northeastern United States.
The technology sector led the day's gains, with the S&P 500 technology index up 1 percent. Gains in LinkedIn Corp and AOL Inc after they reported quarterly results helped the sector.
The market has posted strong gains since the start of the year, with the S&P 500 up 6.4 percent since Dec. 31. But the advance has dragged in recent days, with fourth-quarter earnings winding down and few incentives to continue the rally on the horizon.
"I think we're in the middle of a trading range and I'd put plus or minus 5 percent around it. Fundamental factors are best described as neutral," Dickson said.
The Dow Jones industrial average was up 48.92 points, or 0.35 percent, at 13,992.97. The Standard & Poor's 500 Index was up 8.54 points, or 0.57 percent, at 1,517.93. The Nasdaq Composite Index was up 28.74 points, or 0.91 percent, at 3,193.87, its highest closing level since November 2000.
Shares of LinkedIn jumped 21.3 percent to $150.48 after it announced quarterly profits and gave a bullish forecast for the year.
AOL Inc shares rose 7.4 percent to $33.72 after the online company reported higher quarterly profit, boosted by a 13 percent rise in advertising sales.
The CBOE Volatility index, Wall Street's so-called fear gauge, was down 3.6 percent at 13.02. The gauge, a key measure of market expectations of short-term volatility, generally moves inversely to the S&P 500.
"I'm watching the 14 level closely" on the CBOE Volatility index, said Bryan Sapp, senior trading analyst at Schaeffer's Investment Research. "The break below it at the beginning of the year signaled the sharp rally in January, and a rally back above it could be a sign to exercise some caution."
Signs of economic strength overseas buoyed sentiment on Wall Street. Chinese exports grew more than expected in January, while imports climbed 28.8 percent, highlighting robust domestic demand. German data showed a 2012 surplus that was the nation's second highest in more than 60 years, an indication of the underlying strength of Europe's biggest economy.
Separately, U.S. economic data showed the trade deficit shrank in December to $38.5 billion, its narrowest in nearly three years, indicating the economy did much better in the fourth quarter than initially estimated.
Earnings have mostly come in stronger than expected since the start of the reporting period. Fourth-quarter earnings for S&P 500 companies now are estimated up 5.2 percent versus a year ago, according to Thomson Reuters data. That contrasts with a 1.9 percent growth forecast at the start of the earnings season.
Molina Healthcare Inc surged 10.4 percent to $31.88 as the biggest boost to the index after posting fourth-quarter earnings.