This summer, a swathe of UK investment institutions made it clear they favoured the Royal Bank of Scotland-led consortium offer to buy ABN Amro, the Dutch bank, over the Barclays bid.

That was largely because Barclays’ €61bn (£42bn) offer for the whole of ABN meant issuing 7.6bn shares.

Many investors with holdings in both Barclays and RBS said if they had to favour one bid, the consortium’s €70bn bid was preferable. RBS, after all, was offering only €16bn and mostly cash for the bits it wanted of ABN.

Nonetheless, some shareholders worried that Sir Fred Goodwin, RBS chief executive, who made 23 acquisitions between 2000 and 2006, was beginning to display imperialist tendencies, despite promises he would focus on organic growth.

Scottish Widows Investment Partnership sold much of its 3 per cent stake in the bank early in the bidding process. Threadneedle Asset Management also reduced its holdings.

Three months later these sales appear shrewd after a 4 per cent fall in banking shares and a 10 per cent fall in RBS shares.

The Scottish bank’s bid for ABN – in contrast with Barclays’ share-dominated offer – remains unchanged and RBS now has to justify paying a 46.6 per cent premium to ABN’s undisturbed share price.

One disenchanted shareholder says: “The question is whether RBS is just over-paying or grossly over-paying.

“RBS will have to work very hard to prove this is a good deal.”

Another says: “The company was paying a big multiple for a bank at the top of the investment banking cycle. Now ABN is in worse shape and the cost of finance is rising. Why didn’t RBS at least adjust the price?”

RBS has privately tried to reassure investors ABN is trading well and the Dutch bank presented a one-off opportunity to turn RBS into the world’s foremost corporate bank. It has also bought ABN shares in the market reducing the average cost.

Those close to RBS point out there was no sign of uncertainty in August when 95 per cent of equity investors voted in favour of the bid.

What is more, recent preference share issues to finance the deal were over-subscribed.

Some investors remain sceptical. They worry the shares will continue to trade at a discount to a sector that will struggle next year. Chris White, Threadneedle equity fund manager, argues: “Earnings growth for the sector will be in single digits next year. Loan growth will slow and margins will slip”.

But there are consolations. One shareholder says: “RBS is on a p/e of 8, a yield of 6.5 per cent, with a dividend growing at 15 per cent a year. Where else will you find that? We will live.”

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