The median premium rate for terrorism insurance was down from $37 per million of total insured value in 2008 to $25 per million in 2009.

Construction, hospitality, utility and real estate suffered the highest median premiums rates last year at $50 per million of total insured valued.

In terms of pricing as a percentage of overall property premiums, financial institutions and transportation paid the largest share at 24 percent and 17 percent respectively, the report said.

On the other hand, hospitality firms witnessed the largest decrease from 13 percent in 2008 to 4 percent last year.

Capacity in the standalone terrorism market is estimated to be at $3.76 billion, offering coverage for both TRIA-certified (Terrorism Risk Insurance Act) and noncertified risks.

Insurers remain cautious about accumulating too much terrorism risk, Marsh noted. They continue to avoid gathering too much exposure in "high-profile urban" areas, and are concerned with "the residual risk of terror events."

Reinsurers offer terrorism risk on a stand-alone basis and an estimated $700 million of per-occurrence is available, the report said.

Marsh said captives are viable vehicles for companies to cover terrorism exposures, especially as a way to control the cost of the program.

In its report, Marsh said the industry still needs a number of years in the future to develop the surplus needed to cover another Sept. 11 event, and a public and private sector program will be needed long-term, otherwise, without that partnership, an economic downturn is a real possibility.