This is what you need to know before the bell:
1. United Airlines (UA) CEO Oscar Munoz testified before the House Transportation Committee on Tuesday. During the hearing, Munoz laid out what United and other airlines could do to win back customer transportation.
2. Apple's (APPL) earnings report beat analysts' estimates but the company reported a surprising fall in iPhone sales, sending shares down in premarket trading
3. Emmanuel Macron and Marine Le Pen are set to go head-to-head in a French presidential debate on Wednesday. Opinion polls show Macron has a 20-point lead as France gets ready to head to the polls
4. The chief executive of Britain's biggest free-to-air commercial broadcaster is stepping down. Adam Crozier announced his departure after seven years in the role at ITV (ITVPY)
5. The Fed is set to conclude a two-day meeting. Investors are expected to focus on discussion of a possible rate hike