Despite successfully emerging from bankruptcy earlier this year, Spirit Airlines is once again facing a turbulent flight path. The budget carrier has issued a stark warning to investors, expressing “substantial doubt” about its ability to continue as a viable business due to persistent financial struggles and a difficult market.

Spirit Airlines CEO Dave Davis addresses employees after an SEC filing showed substantial doubt in the budget carrier's future operations.

After cutting its debt during restructuring, Spirit has tried to attract bookings by marketing more upscale products and looking for new ways to cut costs.