* U.S. shares edge up, extending year-long rally
* Yen hits 5-year trough vs euro, 6-month low vs dollar
* Crude up from recent losses, Brent rallies
LONDON/NEW YORK, Nov 29 (Reuters) - A major index of world equities rose to near a six-year high on Friday, helped by gains in U.S. stocks, on faith in an improving global economy and support from central banks, while U.S. crude oil rebounded from recent declines. The U.S. stock market rose in light trading in what will be an abbreviated session following Thursday's Thanksgiving holiday. The S&P 500 has gained 27 percent so far in 2013, with the seasonally strong month of December to come. Retail stocks were in focus on the traditionally busy shopping day for U.S. stores known as Black Friday. "There's nothing to trade on today, but the market is in a momentum story and the rally doesn't seem to be running out of steam," said Robert Russell, president of Russell & Co in Fairborn, Ohio. The MSCI All-World Index gained 0.25 percent to 402.90, hitting a level not seen since Jan. 2, 2008. Oil rallied, putting Brent crude on target for its biggest monthly gain since August, while U.S. light sweet crude gained $1.41 to $93.71 a barrel after recent declines that have widened the spread between London's Brent contract and U.S. crude. An explosion at an army depot in southern Libya kept supply disruptions in traders' minds, and Brent rose 40 cents to $111.26. Prices for U.S. Treasuries dipped slightly in subdued trading, with investors looking ahead to data next week. The benchmark 10-year Treasury note slipped 6/32 in price to yield 2.7571 percent. The market is scheduled to close early at 2 p.m. Eastern time (1900 GMT). The Dow Jones industrial average rose 58.92 points, or 0.37 percent, at 16,156.25. The Standard & Poor's 500 Index was up 5.58 points, or 0.31 percent, at 1,812.81. The Nasdaq Composite Index was up 21.25 points, or 0.53 percent, at 4,066.00. In the currency market, the euro rose against the dollar to $1.3614. The dollar edged higher to 102.30 against the yen in light volume. Investors have been using the yen as a funding currency for carry trades with the Bank of Japan committed to keeping ultra-loose monetary policy to shore up growth. That is in contrast to the U.S. Federal Reserve, which is moving toward unwinding its $85 billion-a-month bond-buying campaign. The yen is down almost 18 percent versus the euro this year, while it is off 15 percent against the greenback and is also set for its biggest one-month fall since January. The Nikkei meanwhile, has rallied 50 percent this year. European shares were near a 5-1/2 year high and heading for a seventh week in positive territory out of the last eight in a relaxed end to the month. London's FTSE, Madrid's IBEX and Frankfurt's Dax all inched up. Standard and Poor's stripped the Netherlands of its prized AAA grade, blaming its worsening growth prospects, but the bond market reaction was muted with Dutch debt prices rose slightly despite the bad news. Tokyo's Nikkei notched its best November since 2005 despite some late profit-taking in Asia, as the yen, at a five-year low against the euro and a six-month low versus the dollar, boosted hopes for its big exporting firms. Gold rose 1.3 percent to $1,254 an ounce, but the commodity has been under pressure throughout the year, driven by worries over the U.S. Fed eventually scaling back its stimulus.