Elevated jet fuel costs stemming from the Iran conflict that began in February 2026 remain the dominant driver pressuring U.S. airline balance sheets, with incremental expenses exceeding $100 million for some carriers in the first quarter alone. Spirit Airlines, already operating under its second Chapter 11 filing since 2024, ceased all flights in early May after failing to secure a bailout and restructure amid these higher operating costs and reduced passenger demand. Low-cost operators such as JetBlue and Frontier face the steepest near-term liquidity challenges, with analysts citing debt loads projected to reach $9 billion and annual interest expenses climbing toward $800 million at current fuel prices. Major network carriers maintain stronger cash positions and access to capital markets, limiting their immediate distress risk. Traders are monitoring second-quarter fuel price data, FOMC policy signals, and any revisions to summer booking trends as key catalysts that could shift the probability of additional filings before year-end.