Goshawk Insurance Holdings made a pre-tax loss of £316,000 for the six months to June 30, compared to a profit of nearly £4m in the same period last year.
Announcing its interim results last week, the Lloyd's insurer's gross written premium for the period rose to £102.9m from £59.4m the year before, an increase of 73%.
It made a technical profit of £2.7m on continuing operations.
Chairman David Hooker said its losses from the September 11 terrorist attacks were “containable”.
Finance director Chris Fagan said the gross exposure came to about $20m (£13.5m).
He said the firm had escaped large direct losses on both the terrorist attacks and the subsequent stock market crash.
He said: “We had no direct exposure to the property or the business interruption insurance on the World Trade Centre.
“We weren't writing the building, but we did write the aviation war insurance and our exposure came mainly from the aircraft hulls.”
He said the company had been holding the bulk of its investments in fixed income securities rather than shares.
He said Goshawk was well placed to take advantage of soaring rates. He said UK provincial property rates were rising at up to 40%.
He added: “We are increasing our syndicate capacity for next year to £185m from £150m this year.
“Our syndicates have consistently outperformed the Lloyd's average. We have a strong underwriting team and we're confident for the future.”
The company confirmed it would pay an interim dividend of 1.4p a share. Its net assets per share for the period being reported on were 105p.
Last Friday, shares in Goshawk were trading at 72p on the London Stock Exchange and had risen 2.17% since close of trading the day before.