Incomplete oil data upsets markets

Unreliable data on oil production—starting with the world’s largest exporter, Saudi Arabia—are adding to the price volatility triggered by unrest in the Mideast, despite efforts to improve transparency.

Saudi Arabia said on Sunday that its production had been at least 700,000 barrels a day lower in March than existing estimates, including those published by the Organization of Petroleum Exporting Countries. The surprise news pushed the price of oil down by more than $1 per barrel Monday morning.