Southwest Airlines shares tumble after massive flight cancellations

Shares of Southwest Airlines fell more than 3% in pre-market trading on Monday after canceling more than 2,000 flights since Saturday, disrupting the travel plans of thousands.

Southwest canceled 347 flights on Monday, up from 1,124 on Sunday, or 30% of its schedule, according to flight tracking site FlightAware.

The airline has previously announced that it will cut its fall hours to avoid cancellations and delays that hampered operations during the summer. Now the airline is wondering if it should cut further.

Dallas-based airline president Mike Van de Ven told staff on Sunday night that Southwest is still understaffed and “we will have to continue to adjust our schedules as this environment changes.

“We have already made significant reductions from our previously published November and December schedules, and if we think we need to do more, we will,” Van de Ven said in a recorded message to employees, which was reviewed by CNBC.