* Oil falls under $50 a barrel to three-year low
* Debt rallies after U.S. jobless data raises growth fears
* 10-year Treasury note yield at five-decade low
* U.S. dollar, euro extend losses vs yen on risk aversion (Adds close of U.S. markets)
By Herbert Lash
NEW YORK, Nov 20 (Reuters) - Fear of a deep global slowdown ripped through financial markets on Thursday, wiping out a decade of U.S. stock market gains and driving yields on government debt to record lows as aversion to risk exploded.
A bearish U.S. jobs report intensified concerns of a long recession and crushed expectations for energy demand, sending crude oil down more than 7 percent to below $50 a barrel.
The bleak economic outlook triggered technical breaches by major stock indexes around the world, which could unleash even greater turmoil as sentiment among investors darkens and threatens to spiral markets into a deeper worldwide slump.
"You have fear in the market that you haven't had since the 1930s," said Bryan Taylor, chief economist with Global Financial Data in Los Angeles.
Investors stampeded into low-risk assets as they abandoned stocks for U.S. government debt and the risk-averse yen. Ultra-short bill rates fell toward zero percent and two-year yields set a series of record lows.
The S&P 500, the benchmark for U.S. institutional investors, fell to its lowest closing level since April 1997, while other U.S. indexes and benchmarks in Europe and Asia set 5-1/2-year lows. Almost one out of every two of the 3,249 issues traded on the New York Stock Exchange hit 52-week lows.
The Wilshire 5000 index, the broadest measure of U.S. stock markets, has now fallen by more than 50 percent since its peak on Oct. 9, 2007. The fall is more than when the dot-com bubble burst from March 2000 to October 2002, the start of a five-year rally.
Shares of corporate icons Citigroup, General Motors and Ford plunged anew as all three traded below $5 a share, before news of possible legislation to help the automakers led GM and Ford, which almost fell below $1, to rebound sharply.
Democratic Congressional leaders later indicated they may not go along with the terms of a proposed bailout.
Ford <F.N> climbed 10.3 percent, GM <GM.N> rose 3.2 percent and Citigroup <C.N> shed 26.4 percent to close at $4.71.
Debt yields also fell to record lows. The 30-year U.S. Treasury bond declined to lows last seen in the early 1960s, and the U.S. 10-year Treasury note fell to its lowest in five decades.
U.S. credit default swaps widened to levels that suggest investors expect the worst wave of investment-grade corporate bond defaults since at least 1980.
Fresh economic data reinforced the market gloom. The Conference Board's index of Leading Economic Indicators fell to its lowest reading in four years in October, factory activity in the U.S. Mid-Atlantic region fell to an 18-year low in November, and the number of American workers lining up for first-time jobless benefits surged to a 16-year high last week.
"Anxiety about the financial markets is shifting to anxiety about fundamentals and the real economy, and that's keeping the overall levels of risk aversion very high," said Vassili Serebriakov, currency strategist at Wells Fargo in New York.
"We've had disappointing U.S. economic data and we believe the bear market in equities will continue, lending more support to the dollar and yen."
The Dow Jones industrial average <
> closed down 444.99 points, or 5.56 percent, at 7,552.29. The Standard & Poor's 500 Index <.SPX> fell 54.14 points, or 6.71 percent, at 752.44. The Nasdaq Composite Index < > shed 70.30 points, or 5.07 percent, at 1,316.12.Declining shares beat advancing stocks by 13 to 1.
The picture in Europe was no better. Commodities, a harbinger of global economic growth, were among the biggest losers on the index of leading European companies.
The FTSEurofirst 300 <
> index of top European shares closed down 3.8 percent at 781.06 points. The index has shed about 48 percent so far this year."Emerging markets are falling apart, nobody knows when the currency bleeding is going to stop. There is hardly any ray of hope on the horizon," said Franz Wenzel, strategist at AXA Investment Managers in Paris.
Among European mining companies, Vedanta Resources <VED.L> plunged almost 13 percent, Xstrata <XTA.L> shed more than 11 percent, while Kazakhmys <KAZ.L> and Rio Tinto <RIO.L> each lost about 10 percent.
Oil stocks also weakened as crude prices <CLc1> plunged.
Total <TOTF.PA> and BP <BP.L> fell 4.4 percent and 4.9 percent, respectively.
With economies weakening worldwide, Deutsche Bank said crude oil could fall to as low as $40 a barrel next year.
"Further weakness can be expected for crude oil if global markets continue to march on their deep spiral south," said Chris Jarvis, senior analyst for Caprock Risk Management in Hampton Falls, New Hampshire.
U.S. crude <CLc1> fell $4 to settle at $49.62 a barrel while London Brent crude <LCOc1> shed $3.64 to settle at $48.08 a barrel. Both posted their lowest closes since May 2005.
The benchmark 10-year U.S. Treasury note <US10YT=RR> jumped almost 3 points in price to yield 3.00 percent. The 2-year U.S. Treasury note <US2YT=RR> rose 5/32 in price to yield 0.98 percent.
The dollar rose against a basket of major currencies, with the U.S. Dollar Index <.DXY> up 0.49 percent at 88.233. Against the yen, the dollar <JPY=> fell 1.93 percent at 94.05.
The euro <EUR=> slipped 0.53 percent at $1.2456.
"The price action in the stock market just reinforces the fact that there's a lot of negativity out there," said Joe Francomano, vice president of foreign exchange at Erste Bank in New York. "So you're seeing the risk aversion trades -- dollar and yen -- perform well."
Risk aversion benefits the yen as investors pull money out of higher-yielding assets such as stocks and commodities, positions that were financed with a cheaply borrowed yen.
U.S. gold futures ended nearly 2 percent higher on physical gold bullion buying in spite of a broad decline in commodities, a strong dollar and further losses in equity markets.
The December contract for gold <GCZ8> settled up $12.70 to $748.70 an ounce in New York.
Overnight in Asia, Japan's Nikkei average <
> dropped nearly 7 percent.The MSCI All-Country World Index <.MIWD00000PUS> was down 6.08 percent at 190.34. (Reporting by Leah Schnurr, Richard Leong, John Parry, Steven S. Johnson, Frank Tang and Edward McAllister in New York and Rebekah Curtis and Pratima Desai in London; writing by Herbert Lash; Editing by Leslie Adler)