The Financial Services Authority today warned that it cannot be certain that any new owner of the London Stock Exchange would choose to be regulated in the UK in the long term.

In a detailed examination of the long-term implications of the potential takeover, Callum McCarthy, FSA chairman, said a change of regulator could have dramatic implications for the listing regime for companies, as well as investigations into market abuse, the highly-successful Alternative Investment Market and the role of the Takeover Panel and the Takeover Code.