* U.S., European shares fall on bank, earnings concerns
* Dollar, yen gain on risk aversion before U.S. earnings
* Bonds rise as safe-haven buying returns
* Oil falls below $50 amid concerns about economic growth (Recasts with U.S. markets, changes dateline, previous LONDON)
By Herbert Lash
NEW YORK, April 7 (Reuters) - U.S. and European stocks fell on Tuesday on lingering banking concerns and ahead of what is expected to be a dismal corporate earnings season, causing investors to shun risky assets in favor of safe havens such as the dollar.
Oil fell below $50 a barrel, tracking losses in stocks, as investors tried to gauge the strength of the global economy as revised data showed the euro zone's gross domestic product shrank more than earlier estimated in the fourth quarter, pointing to an even worse 2009 figure.
U.S. Treasuries rose as the dour outlook for stocks and rising concern over the poor quality of assets still haunting major banks enhanced the safe-haven allure of government debt.
Jitters regarding financial companies have resurfaced as investors gird themselves for the first-quarter earnings reports of U.S. companies, ahead of its traditional start with Alcoa Inc <AA.N> after the market's close on Tuesday.
Alcoa shares fell 2.2 percent.
"It's quite clear that risk aversion is driving the market, that's why we're seeing gains in the dollar and yen," said Matthew Strauss, senior currency strategist at RBC Capital Markets in Toronto.
"There is caution ahead of the earnings season," he said.
Shortly after midday, the Dow Jones industrial average <
> was down 159.93 points, or 2.01 percent, at 7,815.92. The Standard & Poor's 500 Index <.SPX> was down 14.08 points, or 1.69 percent, at 821.40. The Nasdaq Composite Index < > was down 27.95 points, or 1.74 percent, at 1,578.76.Concerns about global growth also weighed on the stock market, with oil giants Exxon Mobil <XOM.N> and Chevron <CVX.N> among the largest drags on the Dow as oil fell.
Exxon fell 2.4 percent to $68.35, and Chevron fell 2.3 percent to $68.28.
European shares fell for a third straight session as financial shares slipped ahead of the earnings season on renewed worries about their balance sheets.
The FTSEurofirst 300 <
> index of top European shares closed 0.7 percent lower at 761.69 points.Banks were among biggest losers. Standard Chartered <STAN.L> fell 6 percent, Lloyds <LLOY.L> slipped more than 7.8 percent and UBS <UBSN.VX> shed 5.2 percent.
"There are still a number of major outstanding question marks on what the authorities are going to do to mend the banking system," said Jonathan Lawlor, head of European research at Fox-Pitt, Kelton.
"It looks to be premature to call the bottom even if the rate of descent and deterioration has seemingly slowed," he said.
Crude oil has closely tracked the fortunes of broader markets as investors look for clues as to when demand might rebound.
"I think the road to recovery is a long one, and while we await a recovery, global oil demand will be weak," Bache Commodities broker Christopher Bellew said.
GDP in the 15 countries using the euro in the fourth quarter contracted a record 1.6 percent from the previous three months, more than the previously reported 1.5 percent.
U.S. light sweet crude oil <CLc1> fell $1.24 to $49.81 a barrel.
The yen rebounded broadly and sharply, with short-term players unwinding trades in higher-yielding currencies such as the Australian and New Zealand dollars that had been financed with the Japanese currency because of its low interest rates.
The dollar rose against a basket of major currencies, with the U.S. Dollar Index <.DXY> up 0.54 percent at 85.203. Against the yen, the dollar <JPY=> was down 0.32 percent at 100.66.
The euro <EUR=> was down 0.98 percent at $1.3274.
A report by The Times of London that said the International Monetary Fund was set to forecast toxic assets on the balance sheets of financial firms could reach $4 trillion helped push bond prices higher.
Whatever the final tally of bad assets, few investors are willing to bet there are no more nasty surprises lurking in the U.S. banking sector.
The benchmark 10-year U.S. Treasury note <US10YT=RR> rose 6/32 in price to yield 2.91 percent. The 2-year U.S. Treasury note <US2YT=RR> added 2/32 in price to yield 0.92 percent.
Copper, a barometer of global growth, bucked the trend and rose after a new drop in inventories suggested Chinese demand is rising, but the rally eased as stock losses curbed sentiment.
"Copper looks good," said Andrey Kryuchenkov, an analyst at VTB Capital. "The Chinese will keep buying for infrastructure programs, but I'd be very wary that we are still a little bit in a bear rally."
Stocks snapped a five-day rally overnight in Asia, picking up on renewed concerns about the health of U.S. banks that rattled investors in the United States and Europe on Monday.
The MSCI index of Asia Pacific stocks outside Japan <.MIAPJ0000PUS> fell 1.25 percent while Japan's Nikkei share average <
> slipped 0.3 percent. (Reporting by Chuck Mikolajczak, Gertrude Chavez-Dreyfuss and Burton Frierson in New York; Jamie McGeever, Atul Prakash, Emelia Sithole-Matarise, David Sheppard, Veronica Brown, Rebekah Curtis and Michael Taylor in London; writing by Herbert Lash; Editing by Leslie Adler)