HARTFORD, Conn. (AP) – Aetna Inc. announced Friday that it has agreed to acquire HMS Healthcare, a regional health care network, for about $390 million.

The acquisition will enable the Hartford-based insurer to strengthen its local market presence, particularly in Michigan and Colorado, company officials said.

The transaction has been approved by HMS Healthcare’s board of directors and stockholders and is subject to customary closing conditions and federal antitrust regulatory approval. Aetna expects to close the transaction during the third quarter.

“Aetna is committed to giving employers and individuals in Michigan and Colorado access to affordable, high-quality health care,” said John W. Rowe, Aetna chairman and chief executive. “It also should position Aetna to compete strongly in the markets served by HMS Healthcare.”

In Michigan, HMS networks serve more than 1 million residents.

“This acquisition simultaneously meets two of our stated objectives for strategic acquisitions: it enables us to enter an attractive new market segment and improve our local position in important geographic markets,” said Ronald A. Williams, Aetna president.

HMS has about 400 employees, about two-thirds based in Michigan and one-third in Colorado. Aetna said it intends to retain key HMS management.

“Since HMS will operate as an independent company, we anticipate few redundancies,” said Fred Laberge, an Aetna spokesman.

Shares of Aetna closed Friday on the New York Stock Exchange at $82.16, down 92 cents and close to the high end of its 52-week range of $39.02 to $86.47.