Check out which companies are making headlines before the bell:
Cigna—Cigna rejected Anthem's $47 billion takeover proposal. It said its rival's bid was "not in the best interest of shareholders" and added it was "deeply disappointed" in Anthem's recent actions in pursuing a deal with Cigna. This flurry of activity comes as Cigna and Aetna vie to buy Humana.
Williams Companies—Williams said it has rejected an unsolicited $48 billion buyout bid from an unnamed company, but that it is open to other offers. Reports say the unnamed suitor is Energy Transfer Equity.
Priceline Group, Expedia—Deutsche Bank upgraded Expedia to "buy" from "hold," and cut Priceline to "hold" from "buy." The bank sees more limited upside to Priceline shares with the company operated at peak efficiency, and with possible negative impact from the growth of Airbnb. Expedia, meanwhile, is benefiting from an improving core business, according to the report.
Apple—Apple reversed its policy and now plans to pay music artists royalties during the free trial period for its new Apple Music service.
American Airlines, Delta Air Lines, United Continental, and Southwest Airlines—Airline stocks could rise 15 percent to 50 percent due to lower fuel costs and a lack of competition, according to Barron's.
Advanced Micro Devices—The chipmaker is considering various strategic alternatives, including a breakup or a spin-off of various businesses, according to Reuters.
Honda—The automaker has linked an eighth death to defective airbags made by Japan's Takata.
Facebook—Facebook will unveil new mobile ad formats at an advertising conference in Cannes, France today.Microsoft will unveil new content related to its "HoloLens" technology at that same conference.
Fitbit—The maker of wearable fitness devices is jumping in premarket trading this morning, after chalking up gains in its first two days as a public company at the end of last week.