(Updates throughout, adds Wall Street outlook)
By Jeremy Gaunt, European Investment Correspondent
LONDON, Jan 24 (Reuters) - Investors poured back into equities on Thursday, hoping a rescue plan for ailing bond issuers would stop a new round of credit losses, although claims of a massive trade fraud added to financial sector worries.
Wall Street looked set to open higher and demand for bonds fell sharply as equities rebounded. The dollar weakened.
Societe Generale <SOGN.PA>, meanwhile, said an "exceptional fraud" by one of its traders would cost the group 4.9 billion euros ($7.16 billion).
European and Asian stocks markets took their cue from overnight gains on Wall Street to rise sharply. The pan-European FTSEurofirst 300 <
> was up 4.9 percent and Japan's benchmark Nikkei < > closed 2.1 percent higher.The key driver was news that New York's insurance regulator had pressed major banks on Wednesday to put up billions of dollars to support wobbly bond insurers.
Insurers have become the latest sector to worry investors in the credit crisis. The debt they underwrite shares the top rating of many of these firms, so if the firms are downgraded because of losses, the debt rating goes down too.
This would force some investors to sell, dumping billions of dollars of municipal bonds, repackaged loans and the like onto markets, sending borrowing costs soaring and forcing more investor write-downs.
"If these (insurance) guys would fail, it would be much more catastrophic for banks' balance sheets and we would see another round of write-downs," said Edmund Shing, strategist at BNP Paribas in Paris.
Investors are also still digesting the U.S. Federal Reserve's emergency 75 basis point cut in benchmark interest rates on Tuesday with expectations of more to come.
Japan's market, meanwhile, was boosted by discussions among the country's ruling party about helping the stock market recover. The draft proposals included a call for the Bank of Japan to cut interest rates to zero again.
Overall, the new optimism wiped away some of this week's sharp losses on bourses. European investors, however, were rattled by the alleged fraud at Societe Generale, one of the biggest in financial history.
As well as the 4.9 billion euro cost, SocGen announced plans to raise 5.5 billion euros through a capital increase to shore up its balance sheet, also reeling from a crisis in global credit markets.
SocGen shares were down 4 percent after earlier being suspended.
BETTER IFO
European markets were little changed by a better-than-expected Ifo economic research institute report on German business confidence.
Euro zone government bond tumbled as stocks bounced back and European Central Bank Governing Council member Axel Weber made hawkish comments interpreted as lowering the likelihood of ECB rate cuts.
"If equities hold up on the back of this bond insurers rescue package, then it is going to be hard for bond markets to generate any upward price momentum so the risks would be for a bigger short-term pull-back," said ABN AMRO rate strategist Jason Simpson.
Two-year Schatz yields <EU2YT=RR> were 16 basis points higher at 3.394 percent, while 10-year yields <EU10YT=RR> were 7 basis points higher at 3.981 percent.
The euro climbed against the dollar <EUR=>, up a third of a percent at $1.4686. The dollar was flat at 106.68 Japanese yen <JPY=>. The euro rose a third of a percent to 156.61 yen <EURJPY=>.
(Editing by Ruth Pitchford)