Sept 8 (Reuters) - U.S. gold futures hit $1,000 an ounce for the first time since February as the dollar's weakness, concerns about the sustainability of global economic recovery and worries about future inflation underpinned sentiment. Following are key facts about the market and different ways to invest in the precious metal. HOW DO I INVEST? SPOT MARKET Large buyers and institutional investors generally buy the metal from big banks. London is the hub of the global spot gold market, with some $18 billion in trades passing through London's clearing system each day. To avoid cost and security risks, bullion is not usually physically moved and deals are cleared through paper transfers. Other significant markets for physical gold are India, China, the Middle East, Singapore, Turkey, Italy and the United States. FUTURES MARKETS Investors can also enter the market via futures exchanges, where people trade in contracts to buy or sell a particular commodity at a fixed price on a certain future date. The COMEX division of the New York Mercantile Exchange is the world's largest gold futures market in terms of trading volume. The Tokyo Commodity exchange, popularly known as TOCOM, is the most important futures market in Asia. China launched its first gold futures contract on January 9, 2008. Several other countries, including India, Dubai and Turkey, have also launched futures exchanges. EXCHANGE-TRADED FUNDS The wider media coverage of high gold prices has also attracted investments into exchange-traded funds (ETFs), which issue securities backed by physical metal and allow people to gain exposure to the underlying gold prices without taking delivery of the metal itself. Gold held in New York's SPDR Gold Trust <GLD> <XAUEXT-NYS-TT>, the world's largest gold-backed ETF, rose to a record high of 1,127.68 tonnes on April. The ETF's holdings are equivalent to nearly half global annual mine supply, and are worth some $34 billion at today's prices. Other gold ETFs include iShares COMEX Gold Trust <IAU>, ETF Securities' Gold Bullion Securities <GBSx.L> and ETFS Physical Gold <PHAU.L>, and Zurich Cantonal Bank's Physical Gold <ZGLD.S>. BARS AND COINS Retail investors can buy gold from metals traders selling bars and coins in specialist shops or on the Internet. They pay a small premium for investment products, of between 5-20 percent above spot price depending on the size of the product and the weight of demand. KEY PRICE DRIVERS: INVESTORS Rising interest in commodities, including gold, from investment funds in recent years has been a major factor behind bullion's rally to historic highs. Gold's strong performance in recent years has attracted more players and increased inflows of money into the overall market. U.S. DOLLAR The currency market plays a major role in setting the direction of gold, with bullion prices moving in the opposite direction to the U.S. dollar. Gold is a popular hedge against currency weakness. A weak U.S. currency also makes dollar-priced gold cheaper for holders of other currencies and vice versa. OIL PRICES Gold has historicaLly had a strong correlation with crude oil prices, as the metal can be used as a hedge against oil-led inflation. Strength in crude prices also boosts interest in commodities as an asset class. POLITICAL TENSIONS The precious metal is widely considered a "safe-haven", bought in a flight to quality during uncertain times. Major geo-political events including bomb blasts, terror attacks and assassinations can induce price rises. Financial market shocks, which cause other asset prices to drop sharply, can have a similar effect. CENTRAL BANK GOLD RESERVES Central banks hold gold as part of their reserves. Buying or selling of the metal by the banks can influence prices. In March 2004, 15 European central banks renewed a 1999 pact to limit their gold sales over a five-year period to 2,500 tonnes, with annual sales limited to 500 tonnes, up from 2,000 tonnes in the first agreement. Sales under the pact have been relatively low in recent years, however. In 2007-2008 the signatories of the pact sold only 358 out of a possible 500 tonnes, and sales this year have reached only 144 tonnes so far this year, according to the latest figures available from the World Gold Council. A third Central Bank Gold Agreement was announced in August, which limits the signatories' sales to 400 tonnes a year. HEDGING Several years ago when gold prices were languishing around $300 an ounce, gold producers sold a part of their expected output with a promise to deliver the metal at a future date. But when prices started rising, they suffered losses and there was a move to buyback their hedging positions to fully gain from higher market prices -- a practice known as de-hedging. Significant producer de-hedging can boost market sentiment and support gold prices. SUPPLY/DEMAND Supply and demand fundamentals generally do not play a big role in determining gold prices because of huge above-ground stocks, now estimated at around 158,000 tonnes -- more than 60 times annual mine production. Gold is not consumed like other commodities. Peak buying seasons in major consuming countries such as India and China exert some influence on the market, but others factors such as the dollar and oil prices carry more weight. (Compiled by Atul Prakash and Jan Harvey; editing by Ben Tan) ((ben.tan@thomsonreuters.com; +65 6870 3923; Reuters Messaging: ben.tan.reuters.com@reuters.net)) ((If you have a query or comment on this story, send an email to news.feedback.asia@thomsonreuters.com)) Keywords: MARKETS GOLD/INVESTMENT | 
