Spirit Airlines has raised concerns about its ability to continue operating, issuing a 'going concern' warning in its latest quarterly report. This indicates the airline believes there is substantial doubt about its capacity to meet its financial obligations in the foreseeable future without securing additional funding. The warning comes amidst ongoing challenges in the airline industry, including fluctuating fuel prices and intense competition. Investors are closely watching Spirit's next steps as it seeks to improve its financial position and ensure its long-term viability.