The National Pension Reserve Fund (NPRF), which operates on behalf of the taxpayer, had its best run for years as the recent surge in world stockmarkets boosted the value of its €15.47bn assets by up to €1.5bn.

It represents potentially the only good news for the public finances as the government prepares to inject €3.5bn into AIB and an undetermined amount into other banks. The other banks that are likely to need fresh funds are Anglo Irish and irish Nationwide.

But doubts remain about whether the world stockmarket rally will last much beyond this month and recent gains by financial stocks may "fizzle out", international stockmarket watchers warn. According to Sunday Tribune calculations the value of the €9.8bn the fund has invested in stockmarkets and other market-related assets, including commodities and property, climbed by almost €1.5bn since the end of March to this weekend.

The fund, which now has a huge chunk of its remaining assets placed on world stockmarkets after selling down its holdings of government bonds tapped the huge 15% surge in major world stock indices in the last five weeks.

At the end of March, the fund publicly disclosed it had assets worth €15.47bn, including the €3.6bn in preference shares and warrants it holds in Bank of Ireland and just over €1bn it holds in bonds.

Since March the rally in world stockmarkets has been one of sharpest for years, with British stockmarket prices surging 40% from the lows they hit in early March. But Capital Economics in London has warned that the recent rally has "barely erased" a quarter of the markets' slide since major US stocks hit their peak in October 2007.

"A more sober assessment is that barely more than a quarter of the overall 58% slide in the S&P 500 index since its peak in October 2007 has been erased. We suspect the latest rebound in financial stocks – which have fuelled the rally – may soon fizzle out," they said.

Investors appear to have grown excited by the prospects of a swift recovery in the US.