Traders on the floor of the New York Stock Exchange.

Family Dollar —Investor Carl Icahn revealed a 9.4 percent stake in the discount retailer. That makes Icahn the company's largest shareholder, and he said he may seek representation on the board. Activist investor Nelson Peltz is also a major Family Dollar shareholder. Following that move, Jefferies upgraded both Family Dollar and rival Dollar General to "buy" from "hold."

Check out which companies are making headlines before the bell:

Valeant–Activist investor Bill Ackman told CNBC's Squawk Box that Valeant is a much greater value proposition than your typical pharma company, with only 15 percent subject to a so-called "patent cliff." Valeant, in partnership with Ackman, is attempting to buy Allergan.

Chesapeake Energy–The company's board of directors has approved the spin-off of Chesapeake's oilfield services business into a separate publicly traded company called Seventy Seven Energy.

Hittite Microwave–Chipmaker Analog Devices is buying Hittite for $78 per share in cash. Hittite is a maker of integrated circuits for radio frequency applications.

L Brands–The Victoria's Secret parent is now rated "perform" at Oppenheimer, up from a prior rating of "underperform", citing the company's market-leading brands and the potential for international growth.

Amazon.com–The web retailer launches a new subscription payment service for other companies today, as it continues to encroach turf long dominated by eBay's PayPal. The service allows Amazon customers to store credit card information on Amazon, and use those cards to pay for various monthly services like phone bills.

Credit Suisse–The bank may spin off part of its U.S. fixed income unit, according to a report in the Financial Times.

Apple–Apple's 7-for-1 stock split is effective today, with the new shares having been distributed after Friday's close.

Time–The publishing company begins trading on the New York Stock Exchange today, following its spin-off from parent Time Warner. Wells Fargo issued an "outperform" rating on Time stock ahead of its first day, citing the turnaround experience of Time's management.

Netflix–The video service holds its annual meeting today, with shareholders set to vote on a proposal to split the chairman and CEO roles currently held by Reed Hastings.

Kraft Foods Group–Kraft raised retail prices for its Maxwell House and Yuban coffee prices, following rival J.M. Smucker's move last week.

—By CNBC's Peter Schacknow

Questions? Comments? Email us at marketinsider@cnbc.com