The third hurricane to the hit the Caribbean and the United States this season could push hurricane losses towards $20bn.
Accrued losses from Charley, Frances and now Ivan could add up to one of the worst catastrophe years the insurance market has suffered since Hurricane Andrew in 1992.
A spokeswoman for Risk Management Solutions said: "We are estimating total damage from Hurricane Ivan to be from $3b to $6b."
Costs of this level will add to the $7bn damage bill estimated for Charley and the $3.5bn cost of Frances, with a corresponding effect on the insurance markets.
A senior underwriter said: "With reinsurers now offering more global coverage there will be in an impact on the UK insurance sector despite this being a US loss.
"But rather than seeing rates soar they like they did after the World Trade Center it is likely to lead to a reversal of the recent price decreases, particularly in property."