Four global asset management firms are in the frame to acquire a stake in the UK fund manager Hermes, but the seller, the BT Pension Scheme, is likely to remain a part-owner, according to a person familiar with the deal.

Potential bidders include Federated Investors, a $364bn money-manager based in Pittsburgh; Eaton Vance, based in Boston and looking after $400bn; Old Mutual Asset Management, the US funds arm of the UK-South African insurance giant; and Australian fund manager Challenger, which manages A$70bn. News of the bidders was first reported by Sky News this afternoon.