National health insurer Aetna said it has completed its acquisition of Medicity, a health information exchange technology company.

The deal between Hartford, Conn.-based Aetna and the Salt Lake City-based company was announced Dec. 7, 2010. Aetna said it would cost about $500 million to buy Medicity, which will operate as a separate business within Aetna. Medicity’s existing management will remain.

In buying a health IT company, Aetna joins the growing number of health insurers who are diversifying in response to the likely trimming of their profit margins on health insurance as a result of federal health reform.

Medicity, with offices in Salt Lake City, Alpharetta, Ga., and Scottsdale, Ariz., offers products and services that enable health systems, hospitals, physician practices and health information exchanges to securely access and exchange health care information, improving the quality and efficiency of patient care and reducing unnecessary health care costs, according to an Aetna statement.

Aetna provides health care benefits to about 35.4 million people across the U.S.