Good morning. After 34 years in operation, Spirit Airlines is shutting down. Its parent company, Spirit Aviation Holdings, announced Saturday that it had begun an orderly wind-down and canceled all flights. The company said the decision followed unsuccessful efforts to restructure the business, r aise capital, and pursue transactions that could strengthen its financial position. It cited a “material increase in oil prices” and other business pressures that weakened its outlook, adding that “with no additional funding available,” Spirit had no choice but to begin the wind-down. A possible Trump administration-led rescue deal was not reached. For CFOs, the Spirit story may be less a travel-industry drama than a case study in what happens when a capital-intensive business loses the assumptions that made its model work. In a Fortune article, “How Spirit Airlines’ business model collapsed,” Shawn Tully explains that Spirit built its advantage on ultra-low costs, no-frills pricing, and dense leisure routes. But after COVID-19, a failed Frontier deal, JetBlue’s $3.7 billion offer, and a blocked merger that left management in limbo for two years, the airline emerged with fewer options and less room for error. Spirit first filed for bankruptcy in November 2024 and emerged in March 2025 with a new strategy. “The plan failed, in part because Spirit had a reputation for mediocre customer service at best,” Tully writes. What Spirit offered was not enough to offset that “historical brand deficit and get the extra revenue,” Savanthi Syth, an analyst at Raymond James, told Fortune. By August 2025, Spirit was back in bankruptcy court for the second time in under two years. You can read more of Tully’s analysis here. Another factor was fuel. Spirit built its restructuring plan around jet fuel costs averaging about $2.24 a gallon in 2026 and $2.14 in 2027. As of May 2, jet fuel prices have surged to $4.51 per gallon on average. That is not just a cost spike. It is a stress test of scenario planning, liquidity, and whether a restructuring plan was built for volatility or for hope. Sheryl [email protected] This story was originally featured on Fortune.com ...read more read less