Check out which companies are making headlines before the bell:
Macy's — The retailer's stock tumbled around 10 percent after announcing disappointing holiday sales and a plan to likely cut 10,000 workers. Macy's same-store sales dropped 2.1 percent in November and December, around the low end of its previous guidance.
Kohl's — Kohl's slashed its full-year earnings guidance to a range of $3.60 to $3.65 per share, sending its stock reeling 15 percent.
Alexion Pharmaceuticals — The drug company's shares gained more than 5 percent after Alexion reiterated its sales and earnings guidance for 2016. Alexion said it expects 2016 revenues to range between $3.05 billion and $3.1 billion and adjusted earnings per share between $4.50 and $4.65.
Alphabet — The Labor Department filed a lawsuit against Alphabet's Google unit seeking access to the company's compensation data and documents, specifically to its equal opportunity program.
Walgreens Boots Alliance — The largest drug store chain in the U.S. reported an unexpected drop in quarterly sales, but raised the lower end of its fiscal 2017 earnings range by 5 cents, to $4.90 per share. Separately, Walgreens said it working toward closing its takeover of Rite Aid "in the early part of this calendar year."
Constellation Brands — The maker of Corona and Modelo beers posted a 10.3 percent increase in quarterly sales, helped by strong demand for its high-end beers and the acquisition of Ballast Point, a brewing company in San Diego, California.
Mylan — Analysts at Citi downgraded the drugmaker's stock to "neutral" from "buy," and cut its price target to $44 from $59. Citi said it sees "limited upside" on the stock, citing "the opportunity for meaningful multiple expansion from current levels, given our stance on the generics space in general."
Mastercard — RBC upgraded the credit card firm's stock to "top pick" from "outperform" and hiked its price target to $130 from $115. The analysts cited a possible pickup in earnings and a re-acceleration in sales while operation expenditures slow, among others.
Twilio —Pacific Crest upgraded Twilio shares to "overweight" from "sector weight," citing an "underappreciated growth potential inherent in a usage-based model similar to [Amazon Web Services]." Twilio's stock rose more than 3 percent in premarket trading.
Western Digital — Analysts at BMO upgraded the California-based company's stock to "outperform" from "market perform," and raised its price target to $90 from $66. BMO also said it expects organic revenue growth to return in fiscal 2017.
— Reuters contributed to this report.
Correction: This story has been updated to reflect Macy's same-store sales fell 2.1 percent in November and December.