Oil prices have swung wildly in the past month ahead of the U.S. sanctions against Iran taking effect. But what are the key factors driving the price swings and what comes next?

1. From Famine To Feast?

Just one month ago Brent crude hit a four-year high above $86 a barrel as traders worried that the forthcoming U.S. sanctions on Iran would create a shortage of supplies.

Since then, however, prices have fallen 15% as the market has reassessed the situation.

U.S. oil output has risen faster than expected, while Saudi Arabia, the world’s largest exporter, has increased production close to its highest level on record.