Gen Re Chairman and CEO Tad Montross will step down at the end of this year.

The decision comes amid a worldwide restructure of the Berkshire Hathaway insurance business.

Last month Gen Re announced the reorganisation of its global property and casualty (P&C) operations, under which six regional units will close: Melbourne, Hong Kong, Riga in Latvia and Charlotte, Seattle and St Paul in the US.

P&C President Bob Jones said the closures reflect “the realities of today’s markets” and follow a review of “our entire global footprint”.

Mr Montross’ retirement has also revealed a shift at the top of Berkshire Hathaway.

Whereas he reports directly to CEO Warren Buffett, his successor will report to Ajit Jain, widely regarded as a potential successor to Mr Buffett.

Mr Montross began his career at Gen Re in 1978 as a casualty facultative underwriter. He has been CEO since 2008.