Shares of Bermuda-based insurer XL fell more than 2 percent Tuesday, off nearly 6 percent for the month.
"I believe it's falling off of higher loss estimates from the hurricane," said FBR Capital Markets analyst Randy Binner, who has a neutral rating on XL.
Shares of Puerto Rico-based Triple-S Management, a $500 million market-cap stock, fell more than 2.5 percent Tuesday, off more than 9 percent for the month.
Shares of Bermuda-based Everest Re fell more than 1 percent are are down more than 12 percent for September. Another Bermuda-based insurer, Aspen Insurance, fell more than 2 percent Tuesday.
The insurance stocks fell earlier this month, then briefly recovered after Hurricane Irma turned out to be less damaging than expected.
However, Hurricane Maria last week became the worst hurricane to hit Puerto Rico in more than 80 years.
"Islands in the Caribbean devastated by the storm, and by Hurricane Irma two weeks earlier are in the early stages of what will inevitably be a very lengthy recovery period," the AIR release said. "It is abundantly clear that this has been a major catastrophe for the region."