Check out which companies are making headlines before the bell:
Dollar Tree — The discount retailer missed estimates by 6 cents with quarterly profit of $1.01 per share, with revenue slightly below forecasts in what the company calls a "challenging" macroeconomic environment. Dollar Tree did see a same-store sales increase of 1.7 percent during the quarter.
Marriott, Starwood — The two hotel chains say waiting periods in both the U.S. and Canada have passed without objections to their combination from anti-trust regulations, and that they expect to complete Marriott's purchase of Starwood by the middle of this year.
Medtronic — The medical products maker matched estimates with adjusted quarterly profit of $1.06 per share, and revenue was essentially in line as well. Medtronic said its integration of Covidien is delivering cost synergies that are benefiting the company's overall performance.
Walgreens Boots Alliance — Mizuho upgraded the drug store operator's stock to "buy" from "neutral," pointing to upside earnings potential as well as confidence that the Federal Trade Commission will approve its proposed acquisition of Rite Aid.
AutoZone — The auto parts retailer earned $7.43 per share for its latest quarter, 15 cents above estimates. Revenue was essentially in line, with same-store sales posting an increase of 3.6 percent.
Kate Spade — The clothing, handbag, and accessories maker earned an adjusted 32 cents per share for its latest quarter, matching estimates, though revenue was short of forecasts. The company did report a same-store sales increase of 7.6 percent.
Valeant Pharmaceuticals — The drugmaker confirmed that it was under investigation by the Securities and Exchange Commission. The probe is said to involve its former relationship with drug distributor Philidor Rx Services, although Valeant itself did not give specific details.
Apple — Apple's legal chief and FBI director James Comey will both appear before a congressional panel Tuesday as the two sides make their cases on the ongoing battle over encryption technology. Apple did get a favorable ruling in a New York case, with a judge saying Apple did not have to help officials unlock an iPhone in a drug-related case.
Marathon Oil — The oil producer is planning a secondary offering of 135 million common shares, and will use the proceeds to strengthen its balance sheet and for general corporate purposes.
Crocs — Crocs lost 73 cents per share for its latest quarter, wider than the consensus estimate of a 33 cent loss, although its revenue did beat Street forecasts. The shoe company also gave a revenue projection for the current quarter that falls below analysts' forecasts, as it battles what it calls "near-term challenges."
Workday — Workday lost 1 cent per share for its latest quarter, smaller than the 5 cent loss that analysts were expecting. The maker of human resources software beat revenue estimates, but its current quarter revenue guidance is short of Street forecasts. Workday and other companies in the cloud-computing space have been under pressure amid signs of weak demand.
Hertz Global — Hertz earned an adjusted 5 cents per share for its latest quarter, 1 cent above estimates, but the car rental company's revenue was below forecasts and Hertz said it continues to see soft pricing in the U.S. rental car market for the first quarter of this year. It has now lowered its forecasts for the full year, also citing impact from the weak energy sector.
SunEdison — SunEdison delayed filing its annual report, as an internal investigation into the solar company's finances continues.
Yahoo — Yahoo may write down the value of microblogging site Tumblr, which it bought more than two years ago for $1.1 billion.
IntercontinentalExchange — ICE is considering a bid for the London Stock Exchange, which is currently in advanced talks with Deutsche Borse about a potential $28 billion merger of equals.