Traders work on the floor of the New York Stock Exchange.

Check out which companies are making headlines before the bell:

Twenty-First Century Fox – Fox announced a deal to sell film and TV assets to Walt Disney for $52.4 billion in stock. The companies expect the transaction to close by June 30, 2018.

CBS – Stephens began coverage of CBS with an "overweight" rating, focusing on the advantages of the media company's unique content creation, ownership, and distribution model.

Verizon – HSBC downgraded the stock to "hold" from "buy," saying its recent rally limits any potential upside.

Express Scripts – The pharmacy benefits manager raised its full-year 2017 earnings forecast to an adjusted $7.00 to $7.08 per share from the prior $6.97 to $7.05, compared to the consensus estimate of $7.01 a share. The company also issued a 2018 earnings outlook that comes in largely above consensus forecasts.

Pier 1 Imports – Pier 1 reported quarterly profit of 9 cents per share, 2 cents a share below estimates. Revenue did beat forecasts, but the retailer gave weaker-than-expected current-quarter guidance. CEO Alasdair James said November sales momentum has been fading this month.

Nordson – Nordson came in 5 cents a share above estimates, reporting adjusted quarterly profit of $1.38 per share. Revenue also topped forecasts. The industrial equipment manufacturer forecast a sales increase of 30 percent to 34 percent for the first quarter of 2018.

Delta Air Lines – The airline is expected to announce an order for 100 Airbus A321neo jets, sources said. The order is expected to be announced this morning ahead of the airline's investor day and is seen as a major win for Airbus and a loss for rival Boeing.

Gap Inc. – Gap was downgraded to "perform" from "outperform" at Oppenheimer, which also lowered its price target for the apparel retailer's stock. The firm still sees upside at Old Navy, but struggles at the Gap and Banana Republic chains.

Lululemon – Lululemon was upgraded to "buy" from "hold" at Deutsche Bank, which sees the athletic apparel and footwear sector on more solid ground than previously and that the yogawear maker is on track for more sustained profitable growth across its various operations.

Coca-Cola, PepsiCo, Dr Pepper Snapple – These stocks were among the beverages stocks rated "buy" in new coverage at Deutsche Bank, which said it is taking a constructive view on a sector where market sentiment is biased to the negative side.

Cheetah Mobile – Cheetah announced a deal to incorporate Microsoft's artificial intelligence-based technologies into the mobile internet company's products and services.

Callaway Golf – JPMorgan Chase began coverage on the golf equipment maker with an "overweight" rating, saying Callaway represents a "compelling" double-digit bottom line growth story based on an innovative product portfolio.

Valeant Pharmaceuticals – JPMorgan downgraded the drugmaker to "underweight" from "neutral," with the shares having doubled since reporting third-quarter earnings. JPMorgan points to significant patent erosion concerns that will impact earnings going forward, among other factors.