Insurers, he says, will take a limited amount of risk, dependent on how much reinsurance is available. Capacity would dry up quickly because the risk would be densely concentrated in a geographic area, he notes.

Greenberg says the terrorist bombing of the Boston Marathon would not have an impact on Ace's underwriting of terrorism. He says the company remains thoughtful in its aggregation of risk and the exposures it writes, as it has since it began writing the program in 2001.

He says the bombing, while not destructive in terms of the magnitude of property damage, non-the-less underscores the importance of TRIA, which “allows insurers to more widely offer and underwrite terrorism related exposures.”

Turning to the company's first-quarter results, the Zurich-based insurer reports “a strong start to the year,” says Greenberg. Ace recorded a first-quarter combined ratio of 88.2, an improvement of 1 point over last year.

Compared to a year ago, first-quarter net income dropped 2 percent, or $20 million, to $953 million. After-tax catastrophe losses including reinstatement premiums of $28 million, and a drop in net investment income of 2 percent to $531 million, impacted the results.

Net written premiums were up 6 percent during the first three months to $3.8 billion.