Check out which companies are making headlines before the bell:
Humana — The health insurer earned an adjusted $2.16 per share for its latest quarter, 3 cents above estimates, though revenue missed forecasts. The bottom line was helped by growing membership for the company's Medicare Advantage Business.
Cigna — Cigna came in 8 cents above estimates with adjusted quarterly profit of $2.28 per share, but like fellow insurer Humana, its top line was below Street forecasts. Cigna's results were aided by favorable operating costs.
Youku Tudou — The China-based media company will be bought by Alibaba (BABA) in a deal worth $27.60 per American Depositary Share. The talks between the two companies were made public in mid-October.
Chipotle Mexican Grill — Baird downgraded the restaurant chain's stock to "neutral" from "outperform," on concerns about the impact of the recent E. coli outbreak that has closed several dozen restaurants in the Pacific Northwest.
Walt Disney — Disney reported adjusted quarter profit of $1.20 per share. That beat estimates by 6 cents, but Disney's revenue missed forecasts, despite higher revenues from advertising and its theme parks.
DuPont — DuPont is in separate talks with Syngenta and Dow Chemical about combining agricultural assets, according to Dow Jones. The talks are said to be at an early stage and follow a concerted but failed effort by Monsanto to buy Syngenta.
DreamWorks — DreamWorks earned an adjusted 2 cents per share for the third quarter, surprising analysts who had expected a loss of 5 cents per share. The movie studio's revenue also beat Street forecasts, thanks in part to higher licensing fees for its content.
Shake Shack — Shake Shack beat estimates by 5 cents with adjusted quarterly profit of 12 cents per share. The restaurant chain also scored a beat on the top line and issued strong sales guidance for the current quarter as its comparable restaurant sales surge.
Kraft Heinz — The company fell 18 cents shy of estimates with quarterly profit of 44 cents per share, and missed on the top line as well. The food producer said the strong dollar had a significant negative impact on overseas sales. Separately, Kraft Heinz announced a 4.5 percent dividend increase to 57-1/2 cents per share.
News Corp. — News Corp. missed estimates by a penny with adjusted quarterly profit of 5 cents per share, with revenue for the media company also below estimates. Print ad weakness and the negative impact of the strong dollar both hurt News Corp.'s results.
Monster Beverage — Monster reported quarterly profit of 84 cents per share, 3 cents above estimates, while revenue came in well above estimates as well. The energy drink maker said it was making progress on distribution issues that had disrupted its shipments during the prior quarter.
Weight Watchers — Weight Watchers beat estimates by 10 cents with adjusted quarterly profit of 39 cents per share, while revenue was also above forecasts. The weight loss company also raised its outlook despite an ongoing subscriber decline, and highlighted the recently announced partnership with Oprah Winfrey, saying response has been "terrific".
TripAdvisor — TripAdvisor fell 2 cents short of estimates with adjusted quarterly profit of 53 cents per share, and the travel review site operator's revenue was also short of Street forecasts. TripAdvisor did see increased revenue but also a jump in expenses, as it spent more on advertising, discounts, and loyalty programs.
Nvidia — Nvidia came in 19 cents above estimates with quarterly profit of 44 cents per share, with revenue also above forecasts. The graphics chip maker also gave strong current quarter guidance, with increased demand for its products by the gaming and automotive industries.
Men's Wearhouse — Men's Wearhouse issued a warning that its current quarter earnings will fall considerably below prior estimates, with same-store sales falling up to 25 percent. The clothing retailer is in the midst of overhauling its marketing strategy following the takeover of rival clothing seller Jos. A. Bank.
United Continental — CEO Oscar Munoz announced he would return to work in next year's first quarter. Munoz is on medical leave after suffering a heart attack in October but said he is on the road to recovery.
ZS Pharma — The company will be bought by Britain's AstraZeneca in a $2.7 billion deal. ZS Pharma — a US-based biotech firm — had been in discussions about a possible takeover with Swiss drug maker Actelion.
Towers Watson — The consulting firm is running into opposition to its planned takeover of insurance broker Willis Group. Proxy advisors ISS and Glass Lewis have separately recommended against shareholder approval, saying the consulting firm is paying too little for Willis.
BHP Billiton – The mining company's shares are under pressure, following a dam burst in Brazil that caused damage to a Brazilian iron-ore operation. BHP owns a 50 percent stake.