Goldman Sachs ( GS) is working on a bid for iShares, the manager of exchange-traded funds being auctioned by U.K. bank Barclays ( BCS), a report says.

Bids for the business, which are due by the end of next week, could put a valuation as high as $6.5 billion on iShares, the Financial Times reports, citing a person close to the process.

The newspaper reports Barclays, the U.K.'s third-largest bank, is talking to Goldman and at least three other parties about iShares. These include private capital groups Bain Capital, Hellman & Friedman, and U.S. fund manager Vanguard.

Barclays may provide some financing to the winning bidder on commercial terms to help it fund the purchase, the Financial Times says.

The Hellman & Friedman consortium includes Colony Capital of the U.S. and Apax Partners of the U.K. and is looking at a bid for iShares worth about $5 billion, people familiar with the situation said, the Financial Times reports.