A health insurer is expanding the size of its operations in the Midwest.

Coventry Health Care Inc., Bethesda, Md., has agreed to acquire Preferred Health Systems Inc., Wichita, Kan., a subsidiary of Via Christi Health System Inc. that has about 100,000 commercial group insurance plan enrollees. The carrier also provides administrative services for commercial self-funded plans with 20,000 enrollees.

Coventry is not saying how much it is paying for PHS, but it says it has agreed to continue to use Via Christi and affiliates as network providers.

Once the deal is completed, Coventry will have about 1 million enrollees in the Midwest, the company says.

Coventry hopes to get the regulatory approvals needed to complete the deal within about 4 months.