* Gold, silver rally on safe-haven buying
* AIG, U.S. investment bank shares slump
* GFMS predicts rise in gold prices in fourth quarter
(Adds comment, updates prices)
By Jan Harvey
LONDON, Sept 17 (Reuters) - Gold prices rallied more than 7 percent to a 2-1/2-week high as losses in U.S. investment banking stocks and doubts over the government's bailout of insurer AIG sparked safe haven buying.
Sliding U.S. equity markets and worries about the financial outlook have sparked a flight to "safer" assets, such as bullion, analysts said.
"It looks like (gold) has finally found its safe-haven bid," said Standard Chartered head of commodity research Helen Henton.
Spot gold <XAU=> rose 6.8 percent to $828.30/829.40 an ounce as of 1539 GMT from Tuesday's nominal close in New York of $775.55.
The precious metal rallied sharply after hitting technical stops above $790 an ounce, climbing to a session high of $831.10 an ounce, according to traders.
Gold prices are reacting to deepening fears over the outlook for U.S. investment bans and concerns over the government's rescue plan for AIG, which have sparked fresh buying of commodities.
The U.S. Federal Reserve said in a statement it would extend AIG <AIG.N> $85 billion in exchange for a nearly 80 percent stake to bail it out. [
]But the insurer has posted losses despite the Fed's move, with shares trading down 44.53 percent at 1539 GMT.
Investment banking shares are also suffering, as Lehman Brothers' insolvency earlier this week raises questions about the future of the sector.
FALLING BANK STOCKS
Shares in Wall Street banks Morgan Stanley and Goldman Sachs plummeted as worries over the outlook for the financial sector multiplied, sparking a rise in oil and gold prices.
A spike in interbank lending rates in the United States has added to worry about the global financial system. As financial worries spread, Russia halted stock and bond trading in a response to the worst market falls since 1998. [
]U.S. stocks slid 2 percent, amid fears over falling financial stocks. Morgan Stanley was down 33.97 percent and Goldman Sachs off 21.18 percent at 1540 GMT. [
]With the problems facing investment banks likely to worsen, gold could post further gains as the flight to safety gains strength, analysts said.
"As long as the turmoil in the financial markets continues, and as long as the banks distrust each other... the preference for safe-haven assets is definitely going to continue," said Dresdner Kleinwort consultant Peter Fertig.
The dollar meanwhile weakened, also reacting to a rise in risk aversion among U.S. investors. [
]A softer dollar typically supports gold, which is often bought as an alternative investment ot the U.S. currency.
Precious metals consultancy GFMS said in a report on Wednesday that investment demand was expected to drive gold prices "well above" $900 an ounce in the fourth quarter as the dollar slips and the outlook for the financial sector worsens.
"GFMS expects that a deepening financial crisis coupled with the United States entering a recession -- or close to -- will result in further loosening of U.S. monetary policy," it said. [
]Silver meanwhile tracked gold higher, rising 8.5 percent to a one-week high of $11.34 an ounce before easing to trade at $11.18/11.23 an ounce.
Among other precious metals, spot platinum <XPT=> was trading at $1,065.00/1,085.00 per ounce, up 1.5 percent from Tuesday's close in New York.
Spot palladium <XPD=> was trading unchanged from Tuesday's nominal New York close at $222.50/228.50 an ounce.
(Reporting by Jan Harvey; editing by Christopher Johnson)