Shell reported a 60% drop in profit for the second quarter of 2013, after taking a $2 billion writedown on the value of its liquids rich shale assets. Excluding the charges, Shell's profit was $4.6 billion, declining 20% on the prior year quarter. Shell has the largest investments among oil companies in unconventional sources of oil and gas in the U.S. It is producing 300,000 barrels of oil equivalent a day from unconventional sources, including 50,000 barrels of oil equivalent a day from shale at end of 2012. Shell expects the exploration and production division for the Americas to remain at a loss during the second half of the year because of current oil and gas prices. Shell is now conducting a strategic review to sell around half of its main nine unconventional oil and gas assets in North America.