Robert Pozen, the former vice-chairman of Fidelity Investments and an expert on mutual fund regulation, has been appointed as chairman of MFS Investment Management, the US mutual fund firm which recently settled with regulators over the improper trading practices.

Pozen is replacing Jeffrey Shames who is retiring at the age of 46 after 21 years with MFS, to spend more time with his young family. He said he wanted to see MFS through the settlement before stepping down, having planning a departure for some time.