Upbeat economic news in the US pushed the Dow Jones through 13,000 on Tuesday, the first time it had been at that level since May 2008.
US indices have opened almost 2% higher on the first trading day of 2012 as risk appetite resumes across global markets.
Markets around the world closed down overnight as further signs European leaders will fail to agree a new treaty emerged.
The Dow Jones Industrial Average rose by almost 500 points overnight as US indices jumped following news of co-ordinated central bank action to ease liquidity concerns.
3.10pm: US markets have shrugged off poor third-quarter GDP results with trading muted early in the session.
US shares plunged at opening ahead of an expected announcement politicians have failed to agree a deal to cut the US' sprawling budget deficit.
Moody's has downgraded the credit ratings of 10 German public-sector banks, and taken action against another two, saying there is a lower likelihood the German government will step in with a bailout.
A Federal Reserve official has called for more "monetary accommodation" to tackle surging unemployment and the country's creaking mortgage market.
The FTSE 100 dropped sharply in morning trading as investors fretted over the future of Italy following a spike in the country's bond yields to record levels.
McGraw-Hill and CME Group - owners of S&P Indices and Dow Jones Indexes - have agreed a deal to form a joint indexing venture.