The deal, which is likely to be completed early next year, will lift BP's weighting in the FTSE 100 index by almost two-thirds. Fund managers are concerned that buying by institutional investors will force up the BP share price to unsustainable levels.
The enlarged BP will represent more than 6.6 per cent of the value of the FTSE 100 index, compared with about 4 per cent now. Analysts calculate that, to maintain their current weightings in the stock, UK fund managers will have to spend a further pounds 20bn on BP shares.
Institutional investors are particularly worried that index tracker funds, which hold shares in direct proportion to their representation in an index, will pile into the shares once the deal is cleared, driving up the price. This would drag down relative performance figures for any fund manager caught without a sufficient weighting.
"A number of UK funds have been increasing their weighting," said Salomon Smith Barney analyst Gordon Grey. "If they wait until early next year there may be a further squeeze."
Under the terms of the merger, Amoco shareholders will exchange their shares for shares in BP, which will have its primary stock exchange listing in London.
BP shares, which were one of the most heavily traded shares yesterday, closed up 10p at 880p.Reuse content