According to reports, the index increased by more than 100 points - the equivalent to almost two per cent - to reach 5858 points.
The US authorities agreed to inject the economy with $600 billion worth of capital as part of a bid to aid the economic recovery.
Richard Hunter, head of UK equities at Hargreaves Lansdown Stockbrokers, told the Independent that the decision had led to a surge of positivity within the markets.
"Whether QE2 is going to have its impact in the States remains to be seen, and in terms of the UK, we are getting nearer to the age of austerity.
"Having said that, the third quarter reporting season is under way, and the vast majority of companies have actually exceeded analyst expectations."
Previously, the Federal Reserve provided the economy with $.1 7 trillion worth of stimulus as part of its programme of quantitative easing.
By Jim Ottewill