NEW YORK (AP) -- Just months after emerging from Chapter 11 bankruptcy, Spirit Airlines is warning about its future ability to stay in business.

Spirit Aviation Holdings, the budget carrier's parent company, says it has "substantial doubt" about its ability to continue as a going concern within the next year -- which is accounting-speak for having the resources needed to sustain operations. In a quarterly report issued on Monday, Spirit pointed to "adverse market conditions" that it's continued to face despite recent restructuring and other efforts to revamp offerings.

That includes weak demand for domestic leisure travel, which Spirit said persisted in the second quarter of its fiscal year -- among other challenges and "uncertainties in its business operations" that the Florida-based company expects to continue "for at least the remainder of 2025."

Known for its no-frills, low-cost flights on a fleet of bright yellow planes, Spirit has struggled to bounce back to profitability and boost resources to compete with rivals since the COVID-19 pandemic. Rising operation costs and mounting debt eventually led the company to seek bankruptcy protection in November. By the time of that Chapter 11 filing, the airline had lost more than $2.5 billion since the start of 2020.

When Spirit emerged from bankruptcy protection in March, the company successfully restructured some of its looming debt obligations and secured new financing for future operations. Spirit has continued to make other cost-cutting efforts since -- including plans to furlough about 270 pilots and downgrade some 140 captains to first officers in the coming months.

Those furloughs and downgrades, both announced in July, are set to go into effect Oct. 1 and Nov. 1 to align with Spirit's "projected flight volume for 2026," the company noted in its quarterly report. They also follow previous furloughs and job cuts taken before the company's bankruptcy filing last year.

Despite these and other cost-cutting efforts, Spirit on Monday stressed that it needs more liquidity. As a result, the company said it may also sell certain aircraft and real estate.

Spirit's aircraft fleet is relatively young, which has made the airline an attractive takeover target over the years. But such buyout attempts from budget rivals like JetBlue and Frontier were unsuccessful both before and during the bankruptcy process.

Spirit's shares tumbled more than 40% Tuesday morning, with the company's stock trading at just over $1.80 as of around 11 a.m. ET.