Why Billions in Proven Shale Oil Reserves Suddenly Became Unproven
- U.S. companies erased more than 20 percent of inventories
- Regulator examined estimates as wells lingered on books
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Ultra Petroleum Corp. was a shale success story. A former penny stock that made the big leagues, it was worth almost $15 billion at its 2012 peak.
Then came the bust. Almost half of Ultra’s reserves were erased from its books this year. The company filed for bankruptcy on April 29 owing $3.9 billion.