A trader works on the floor of the New York Stock Exchange.

Allergan –Allergan has settled pending litigation with Pershing Square Capital and Valeant Pharmaceuticals and agreed to hold a special shareholder meeting on December 18. Pershing Square and Valeant are pursuing a hostile takeover of Allergan and had accused the company of trying to avoid that special meeting.

Humana –The managed health care company announced a new $2 billion share repurchase program that extends through December of 2016. It replaces a previous $1 billion program that still had $782 million remaining.

Hershey –Citi added the chocolate maker's stock to its "Focus List," saying Hershey's shares are poised for robust returns after a rough six months which saw Hershey shares fall by 15 percent.

Check out which companies are making headlines before the bell:

Regeneron–The FDA has granted the company's "EYELEA" eye treatment a "breakthrough therapy" designation, after it demonstrated significant improvement in patients with diabetic retinopathy. That designation allows for fast-track approval for companies seeking to market a drug, or expand its approved uses.

Dick's Sporting Goods–The sporting goods retailer announced the retirement of two executives, President and Chief Operating Officer Joseph Schmidt and Executive VP/Global Merchandising John Duken.

Microsoft–RBC began coverage of Microsoft with an "outperform" rating, saying the company is creating value with its shift in emphasis toward cloud and mobile computing.

United Airlines–The airline is offering flight attendants severance packages worth up to $100,000 if they voluntarily leave the company. United will offer the payouts in order of seniority as it works to match staff levels to its flight schedule.

Actavis–New York State attorney general Eric Schneiderman is suing the drug company and subsidiary Forest Labs, attempting to stop the discontinuation of the Alzheimer's drug Namenda from the market. Schneiderman accused the company of trying to maintain a monopoly position by dropping Namenda – soon to lose patent protection – and focusing on a new version known as Namenda XR.

Boeing, Lockheed Martin–A joint venture of the two companies will reportedly announce a partnership with Blue Origin to develop a new rocket engine, according to Reuters. Blue Origin is run by Amazon.com founder Jeff Bezos.

FactSet–The financial information provider earned $1.31 per share for its fourth quarter, beating estimates by a penny. Revenue was also above estimates, and the company said the quarter was one of its best in the past decade.

Alibaba–Alibaba is not yet trading, but the China e-commerce company has raised its IPO price range to $66–$68 per share from the prior $60–$66. It also did not increase the number of shares it planned to offer in its IPO, as many had expected. Alibaba is expected to price on Thursday night and begin trading on Friday.

Wal-Mart—Chief spokesman David Tovar's resignation last week came after the retail giant allegedly discovered falsehoods on his resume, according to a Bloomberg report. Tovar's resume stated that he received a bachelor of arts degree from the University of Delaware in 1996, but an official told Bloomberg that Tovar never received a diploma.

AstraZeneca–The company could earn up to $500 million from a new Alzheimer's drug partnership with Eli Lilly. Lilly will pay AstraZeneca to share rights to the drug, dependent on its success.

Blackstone Group–Blackstone is reportedly seeking to raise $16 billion for a new buyout fund, according to the Wall Street Journal.

Sears Holdings–Sears borrowed $400 million from chief executive officer Edward Lampert's hedge fund, to give it an infusion of cash. According to an SEC filing, the loan comes due on December 31, with the possibility of extending it to February 28.

—By CNBC's Peter Schacknow

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