Photo by Stephen George

Photo by Stephen George

The Wall Street Journal reported Thursday night that Aetna is nearing a deal to purchase Humana, the Louisville-based Fortune 500 company that employs more than 12,000 people here and is the city’s second-largest private employer.

The newspaper reported that a deal could be finalized as soon as tonight, quoting anonymous sources “familiar with the matter.” Those sources cautioned that the timing could change.

Bloomberg reported late Thursday that Aetna is offering $34 billion in cash and stock, valuing Humana shares at roughly $230. That’s a significant premium: Humana shares closed at $187.57 on Thursday, and the company was valued at $28.9 billion. Citing unnamed sources, Bloomberg said the companies have been in negotiations for two weeks, and that a deal could be announced as soon as this weekend.

The reports come as speculation about mergers and acquisitions among the five-biggest U.S. health care companies has intensified in recent weeks.

The Louisville-based company, which has more than 57,000 employees, is said to be an attractive acquisition target because of its large Medicare business. Humana controls 19 percent of that market, serving some 3.2 million members, according to the Kaiser Family Foundation. Nearly three-quarters of its total premiums and revenues in the first quarter of 2015 came via its Medicare offerings, according to SEC filings.

Aetna is based in Hartford, Conn. At $45 billion, it is the second-largest health insurer in the country behind UnitedHealth. It has 1.26 million Medicare members, the Journal reported. An acquisition of Humana would make the company competitive with UnitedHealth, also the industry’s Medicare leader.

The deal would require federal regulatory approval.