Tumbling oil prices have exposed a weakness in the insurance that some U.S. shale drillers bought to protect themselves against a crash.
At least six companies, including Pioneer Natural Resources Co. and Noble Energy Inc., used a strategy known as a three-way collar that doesn’t guarantee a minimum price if crude falls below a certain level, according to company filings. While three-ways can be cheaper than other hedges, they can leave drillers exposed to steep declines.
