Delaware has announced which companies will be participating in its new health insurance marketplace. The exchanges, which are a centerpiece of the Obama administration's health overhaul, go live Oct. 1.

Three insurance companies will offer a total of 19 health plans to Delawareans shopping on the individual market. The plans range from cut-rate, catastrophic coverage with an average monthly premium of $147 to platinum level plans averaging $329 a month.

"I think we have a competitive market with a fair choice," said Linda Nemes of the Delaware Department of Insurance. "I'm excited about the access that Delawareans will have to coverage, and those who may have been left out of that commercial system in the past because of pre-existing conditions will now have the opportunity to have coverage."

But Scott Harrington, a professor of health-care management at Penn's Wharton School, says three insurance companies — two of which (Coventry Health Care and Coventry Health and Life) are related — don't represent much competition.

"That small number is consistent with what's going on in other small states," said Harrington. "For example, in New Hampshire, Vermont and a number of other small states around the country, there are only one or two insurance carriers that are going to be participating."

Harrington says it's harder to make money when populations are small. Still, he said, "there's no reason to think we won't have a bit more competition — and we're certainly not likely to have less competition."

The First State has 90,000 uninsured. Nemes said she expects about a third of that number to sign up for coverage with the private insurers on the new marketplace.