Manufacturers have increased their reliance on other firms to manufacture parts of or components to their end product, and much of that has moved overseas, says Clarke. "So we really just extended existing DPC to this new model" offering second-tier coverage, he says.

It's a concern that didn't exist some five or 10 years ago, and some underwriters do not offer second-tier coverage for Dependent Property today.

"But it's certainly something our customers have been asking us to look into," Clarke says. "When we floated the idea it was very well received, not only by our insurance customers but also by the agents and brokers. They saw it as an important tool to cover their clients."

Even a relatively minor loss down the supply chain can have a significant impact on a company's operations and results. And supply-chain disruption does not only occur when disasters strike in foreign countries.

Recent tornadoes in the Midwest, for example, had a huge effect on aviation manufacturing worldwide, Clarke says.

Spirit AeroSystems Inc., which manufactures airline components for many of the world's airliners, including Boeing Co., suspended production for nine days following an April 14 tornado that damaged its plant in Wichita, Kan. Employees returned to work April 23.

That event, says Clarke, serves as "an example of how just within the U.S. you can certainly have this type of Supply Chain exposure."

The new DPC endorsement, dubbed "Secondary Dependencies," will be triggered by such covered losses as fire, wind, vandalism, riot and strike.

 "Basically, the endorsement says, 'we're going to pay the actual loss of business income you sustain because of a necessary suspension of operation during a period of restoration, for common-type losses at the contributing location, caused by covered cause of loss,'" Clarke explains.

"Or if you've added earthquake or even flood to the policy, as long as it's a covered peril, the secondary coverage will kick in for necessary suspensions caused by those perils," he says. "It pretty much follows the standard trigger—just at the secondary location."

"With business success often riding on the strength of the supply chain, this new coverage option will give insurers the ability to provide a more robust Supply Chain coverage solution to commercial policyholders," adds Kevin Thompson, senior vice president of ISO, in a statement.

The ISO filing has a planned April 2013 effective date for Commercial Property, Capital Assets (output policy) and Agricultural Capital Assets and will be introduced for the Businessowners Program later in 2013.