Share price in Lancashire Holdings dropped as the chairman announced his departure and the company revealed a fall in profits today.
The insurer reported profit before tax for the year ended December 2015 of $171.7m (£119.4m), down from $226.5m for the year ended December 2014, while gross premiums written dropped to $641.1m, compared with $907.6m the year before.
For the company's fourth quarter, profit before tax fell to $50.2m, compared with $91.5m in the same period the year before, while gross premiums written fell to $97.1m, down from $120.4m.
Share price in the company fell steadily throughout the day, trading down 1.8 per cent at 617.5p at around 2pm London time.
Meanwhile, the insurance company's chairman, Martin Thomas, revealed would be stepping down in May. Thomas has been chairman since 2007.
Peter Clarke, who is currently an independent non-executive director for the company and was previously chief executive of Man Group, will be Thomas' successor.
"After nine years, it is the right time for a change, both for the business and for me," said Thomas. "I am delighted to be able to pass on in May the Chairman’s baton to Peter, who brings to the role an acute intellect and an appreciation of the importance of continuing our good governance in creating the space for strategic debate and leadership on the board."
Alex Maloney, Lancashire Holding's chief executive, added: "I would like to thank Martin for his constructive challenge, his strategic insight, his diplomatic skills and on a personal level for his support, good humour and encouragement over many years."