Goldman Sachs is working on a bid for iShares, the fast-growing asset management business that is being auctioned by Barclays.

Bids for the business, which are due by the end of next week, could put a valuation as high as $6.5bn (£4.5bn) on the manager of exchange traded funds – the listed investment vehicles that track a market benchmark, an asset or a basket of shares, according to one person close to the process.