LOUISVILLE, Ky. (WDRB) --  Humana and Aetna shareholders voted separately on Monday to approve the companies’ $37 billion merger. 

Aetna’s purchase of Louisville-based Humana – the biggest corporate headquarters in Kentucky – was agreed to on July 2 and is expected to close in the second half of 2016.

Both companies' shareholders voted 99 percent in favor of the deal, with 82 percent of Aetna's shares voting and 87 percent of Humana's.

While Monday’s approval by investors is a required step, it does not mean the deal is done. 

The U.S. Justice Department and Federal Trade Commission could still block the deal. Government regulators are also looking at Anthem Inc.’s proposed $54 billion purchase of Cigna Corp.

The two mergers, if allowed to go forward, would reduce the nation’s five biggest health insurance companies to three.

The boards of Humana and Aetna had previously recommended that their respective shareholders approve the deal, which values Humana at about $230 per share. Humana traded at about $186 per share on the New York Stock Exchange on Monday.

Humana is Louisville’s most significant corporate headquarters, with more than 12,000 employees in the area.

That will change following the merger, as the combined company’s headquarters and top decision-makers are to be based at Aetna’s home in Hartford, Connecticut.

But Aetna has promised to maintain “a significant corporate presence” in Louisville, where the combined company’s Medicare, Medicaid and TRICARE insurance businesses would be based.

Aetna has also promised investors $1.25 billion in annual cost savings -- or "synergies" -- from combining the companies' operations.

Aetna chief financial officer Shawn Guertin said at a September conference that about $1 billion of the cost savings will come from "SG&A" -- or selling, general and administrative expenses. That's how companies refer to general costs such as employee salaries, office space and advertising.

The Louisville-based government lines of business are expected to bring in 56 percent of the combined company’s $115 billion in annual revenue.

Government programs are Humana’s specialty – particularly Medicare Advantage, which is a privately run version of the government’s health care program for seniors.

Humana has about 3.2 million Medicare Advantage members to Aetna’s 1.2 million. Aetna is much stronger in commercial insurance, with nearly 20 million members, to Humana’s 3 million.

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