This July 12, 2019 file photo shows the UnitedHealthcare headquarters in Minneapolis. Credit: Jim Mone / AP

Federal regulators are suing to block UnitedHealth Group’s purchase of the technology company Change Healthcare, a deal announced more than a year ago.

The U.S. Department of Justice said Thursday that the proposed deal would hurt competition in markets for health insurance and technology used by insurers to process claims and cut costs.

UnitedHealth said in January 2021 that it would spend nearly $8 billion in cash to add the company and boost its ability to provide data analytics and revenue cycle management support, among other offerings.

A UnitedHealth spokesman said Thursday the justice department’s “deeply flawed position is based on highly speculative theories that do not reflect the realities of the health care system. We will defend our case vigorously.”

UnitedHealth Group runs the largest health insurer in the United States. It also operates a growing Optum segment that provides care, manages pharmacy benefits and offers technology support among other things.

Shares of UnitedHealth fell more than 1% in midday trading while broader indexes also dropped.

By Tom Murphy, AP Health Writer