Barclays president Bob Diamond could get a £12.5 million windfall if the bank decides to sell its entire fund management arm Barclays Global Investors, rather than just its iShares offshoot.

Barclays confirmed this afternoon it has received several approaches for BGI.

Diamond, who with the rest of Barclays' top management gave up his bonus for 2008, already stands to make £4.5 million from the sale of iShares. But that payout could almost triple if the whole fund management arm fetches as much as £8 billion.

Management of BGI, led by chief executive Blake Grossman, own shares and options directly in the business. Between them, they stood to make £150 million from the iShares sale, but they could pick up more like £400 million on the sale of the whole of BGI.

Diamond, who heads Barclays investment banking and fund management businesses, took a 99% pay cut last year when he collected just £250,000 in basic pay. The year before, he received over £21 million in pay and bonuses.

BlackRock, the US's largest listed fund manager, is one of the leading potential bidders to buy BGI, which looks after £1 trillion of funds. It is said to be looking at paying from $8 billion (£5.2 billion) to more than $12 billion, according to sources in the US.

Barclays bought what became BGI from Wells Fargo and Nikko for $440 million in 1995.

Other possible bidders include Bank of New York Mellon and American private-equity firms.

The shares shot up 11p at 264p today. They have more than quintupled in value from their low point of 51.2p earlier this year.

Barclays has signed a deal to sell iShares, its hugely successful exchange-traded funds business within BGI, to British venture capitalist CVC for £3 billion.

The bank is putting up part of the money to fund that deal but also agreed with CVC it could look for a higher bidder in a “go shop” exercise. That runs until 18 June and people close to the situation cautioned against making any assumptions over a full-scale bid for BGI appearing immediately. There were 27 original bidders for iShares, and it is believed that many of them have returned to the table either looking at topping CVC's £3 billion offer or bidding for the whole of BGI. If the CVC deal is scrapped, Barclays must pay it a £120 million break fee.

Barclays has avoided going to the Government for bailout funds and passed a Financial Services Authority stress test. But a sale of BGI would significantly strengthen its balance sheet. Barclays has said it is under no pressure to raise extra capital.