US airline stocks experienced significant declines on Monday as crude oil prices surged following the collapse of peace talks between the US and Iran. Benchmark US crude jumped $9.43 to $103.69 per barrel, while Brent crude rose $7.04 to $102.24 per barrel. Delta Air Lines shares fell 3.2%, extending their losing streak to three days, while American Airlines Group, United Airlines Holdings, and Southwest Airlines also saw declines of over 2.5%. The aviation industry is particularly vulnerable to rising fuel prices, which account for more than 50% of operating expenses. Investors had hoped for a resolution to the ongoing conflict in West Asia, but the failure of negotiations has led to renewed tensions. The US has begun blocking ships from entering or exiting Iranian ports in the Strait of Hormuz, a strategic waterway for global oil shipments. President Donald Trump has warned of severe consequences for any Iranian vessels approaching the blockade. With crude oil prices increasing over 40% since March, analysts anticipate continued volatility in fuel costs, which could further impact airline profitability.