Fighting has the potential to disrupt oil markets, but a move by Iran to cut off supply would chiefly hurt China, the biggest buyer of Iranian oil.

The average return on the stocks is negative for the week and month after geopolitical conflicts. The economic risk is higher oil prices, a headwind to global growth.

The oil market has been wrestling for days with Donald Trump’s next act in an escalating Middle East conflict. Now American jets have struck Iran’s three main nuclear sites, a move that leaves traders preparing for a price surge — but still guessing where the crisis goes from here.