Check out which companies are making headlines before the bell:
Humana – The health insurer is in talks with Walmart about closer ties and possibly being acquired by the retail giant, CNBC has confirmed. Talks are said to be preliminary and are focused on new partnerships, although an acquisition is also said to be among the possibilities.
Under Armour – Under Armour informed users of its MyFitnessPal app of a data breach, with 150 million users affected. The athletic apparel maker did say that payment card information was not affected by the breach.
Tesla – Tesla recalled 123,000 Model S cars over possible power steering issues, although the automaker did say that the issue has affected very few of the cars. Separately, Tesla came under fire from the National Transportation Safety Board for releasing information about a fatal crash involving a Model X vehicle that the NTSB is investigating.
Alibaba – Alibaba will buy the part of China food delivery platform Ele.me that it does not already own. Currently, the China-based e-commerce giant owns about 23 percent of Ele.me.
Las Vegas Sands, Wynn Resorts – These stocks could benefit from news that Macau gambling revenue was up 22 percent in March compared to a year earlier, the 20th consecutive monthly gain.
Snap – Snap cut seven percent of its global workforce in March, according to a regulatory filing. The Snapchat parent said it would sustain a $10 million cash expense for severance cost that will be reflected in results for the quarter ending March 31.
Darden Restaurants – The restaurant chain operator was upgraded to "outperform" from "sector perform" at RBC Capital, with the firm citing a number of positive factors for the Olive Garden parent including valuation, appropriate labor investments, and good use of digital technology.
ADP – ADP was upgraded to "outperform" from "sector perform" at RBC, citing valuation for the payroll processing company's shares as well as an improving growth story.
Nike – The athletic apparel and footwear maker is in the process of trying to address and correct a "boys club" culture, according to an article in The Wall Street Journal.
Cal-Maine Foods – The egg producer earned an adjusted $1.27 per share for its latest quarter, 12 cents below estimates, though it did see revenue beat forecasts. Cal-Maine's top line was helped by higher egg prices.
Alkermes – The Food and Drug Administration rejected the company's application for approval of an experimental depression treatment, saying it had not shown sufficient proof of effectiveness. Alkermes said it disagreed with the FDA and would appeal the ruling.
Fitbit – The maker of wearable fitness devices was downgraded to "underweight" from "equal-weight" at Morgan Stanley, saying the company will struggle to stabilize revenue amid an ongoing cash burn.