Insurance Lancashire Group has revealed that recent extreme weather events and natural disasters will cost it up to $212m (£162m).
Meanwhile, one of the world's largest reinsurers, French firm SCOR said the cost of hurricanes Harvey, Irma and Maria, as well as the earthquakes in Mexico, would cost it €430m (£384m).
And catastrophe experts Karen Clark & Company have estimated Hurricane Nate – which made landfall in Louisiana on Saturday – may land the global insurance sector with a bill of $500m.
Lancashire provides global specialty insurance and operates in Bermuda, London and within the Lloyd's market.
The range for its estimated net ultimate losses arising from hurricanes Harvey, Irma and Maria and the two recent earthquake loss events in Mexico is expected to be $106m to $212m.
Lancashire said it has exposure to hurricane risk impacting the US and the Caribbean in the following classes: property retrocession, property direct and facultative, property reinsurance, cargo, marine and energy.
The company said its estimates have been derived from a combination of market data and assumptions, a limited number of provisional loss advices, limited client loss data and modelled loss projections.
“The extensive news coverage turned our thoughts to those whose lives, livelihoods and businesses were devastated by these forces of nature," said Alex Maloney, Lancashire's group chief executive.
"As we assess the financial impact of these losses for Lancashire, these events illustrate the value of our products to our clients. Lancashire’s combination of a strong balance sheet and market leading professional expertise allows us to service the current and future needs of our clients and their brokers and to meet the long term expectations of our investors and broader stakeholders."
Shares in the group were up 1.2 per cent in early trading.