AIB's shares have taken a bit of a battering despite the reasonably strong interim figures posted by the group this week.

Pre-tax profits rose strongly in Ireland and Britain although figures from the US, skewed by a once-off contribution last year and a rebranding exercise, and Poland, where the group is investing heavily in integrating its new purchase, were less favourable. Overall, pre-tax profits rose 7 per cent to €542 million (£427 million)

However, overshadowing all else is the growing belief that AIB will be dropped from the blue-chip Euro Stoxx 50 index, where it has been the sole Irish representative since the index's introduction following the arrival of the euro last January.

Such a move will release many institutions from the need to hold a stake in AIB to track the index of major European companies. The effect on the share price has been exacerbated by a general weakness in banking shares and uncertainty in equity markets worldwide over US intentions on interest rates.