America's wave of new financial regulation is likely to prompt the country's biggest financial institutions to break themselves up, according to the chairman of the Federal Reserve.
The FTSE fell back slightly in early trading on Thursday despite strong overnight showings on Wall Street and in Asia.
The International Monetary Fund (IMF) has warned long-term fiscal reforms will be required among advanced economies as it projected the UK's gross debt to GDP would rise to 90.6% in 2015.
World markets surged on Wednesday following an unexpected jump in US manufacturing data and bullish economic figures from Asia.
The eurozone and US must learn from each other's economic strategies
A cooling global economy and an impending austerity squeeze in Britain will make the Bank of England (BoE) wait well into next year before hiking interest rates, a poll of 60 economists suggests.
The FTSE 100 opened 0.5% higher in early trading on Wednesday after firm economic data from China spurred sentiment.
Leading fund managers have staked their reputations, and their clients' money, on a sustained UK economic recovery by upping their holdings of shares and reducing their positions in bonds in the past month.
US stocks slumped to their worst August in nine years, as investors retreated on fears for the US economy.
More than a tenth of the 7,380 banks in the US remain at risk of failure despite the sector posting strong profit growth during the second quarter.