Ryanair profit slides 34% after jet fuel costs soar, summer fares cut

Brent crude rose 2.5% on Monday, pushing above $90 a barrel for the first time in a month. Traffic through the Strait of Hormuz, a chokepoint for global oil shipments, has stopped.

Shane Oliver, head of investment strategy at fund manager AMP, said the longer the strait remains closed and the conflict escalates, the greater the risk that oil prices will need to rise to around $150 a barrel to balance supply and demand. He called that scenario "not our base case" and "a high risk again."

Ryanair said its full-year results will be "highly sensitive" to further escalation in the Middle East and Ukraine, and to the price of unhedged jet fuel.