Lloyd's syndicates are predicting that the ferocity and frequency of the 2004 hurricane season will drive up falling rates.
Announcing a doubling in pre-tax profit for the six months to 30 June, Atrium chief executive Nick Marsh said that the hurricanes were driving commercial property and energy rates up.
He said he was hopeful the 2004 rate reductions in the property and energy markets would be "short-lived".
Atrium announced a pre-tax profit of £16.1m for the half year, compared to a profit of £8.2m the previous year.
Hardy chairman Peter Hardy said the hurricane losses could end the softening in the catastrophe reinsurance market. Hardy reported a 43% increase in pre-tax profit, to £9.3m for the six months to 30 June, from £6.5m in 2003.