Bloomberg has a look at the borrowing boom underpinning the US shale oil boom - Drillers Piling Up More Debt Than Oil Hunting Fortunes in Shale.

Companies are paying a steep price for the gains. Like Halcon, most are spending money faster than they make it, an average of $1.17 for every dollar earned in the 12 months ended on June 30. Only seven of the U.S.-listed firms in Bloomberg Intelligence’s E&P index made more money in that time than it cost them to keep drilling. These companies are plugging cash shortfalls with junk-rated debt. They owed $190.2 billion at the end of June, up from $140.2 billion at the end of 2011.