The problem was particularly evident among the smallest insurers, those with less than $100 million in assets.

Mr. Lewis said Progressive would talk with smaller insurers that want to be included in the survey.

The bill protects smaller insurers by capping any individual company's liability at 5 percent of its premiums.

"Would smaller insurers find life more difficult if they were not given expected-loss data?"

Some small insurers have made large investments in managed care, just like the big companies, he said.

Alistar, a small insurer in California, is no longer writing new policies.

Only the smallest insurers exist as a single corporation.

By way of contrast, when small insurers fail, they tend to do so in a rather wild and spectacular fashion.

Of course, for small international insurers, economies of scale provided by networks are likely to prove elusive.

Some smaller insurers have long offered the benefit along with recent start-up providers.