4%

That's how much of global oil supply is under threat as Houthi militants threaten shipping through the Red Sea, according to Société Générale.

Iran-banked Houthis have fired on Saudi Arabia-linked vessels in the Red Sea in recent days, threatening the Bab al-Mandeb route that the kingdom has been using to bypass the Strait of Hormuz.

The attacks show the "conflict has entered a more unstable phase rather than moving toward a durable resolution," strategists at Société Générale wrote in a note today. The bank estimates that each month that passes without a resolution will add $10 a barrel to global oil prices.