NEW YORK — At the beginning of the 1980s capital was flooding into the American oil and gas industry. Apache Corporation, an erstwhile conglomerate spanning steel, dude-ranching and car sales, sought to tap into the flow in a novel way. It wrapped a bunch of private oil and gas assets into a new ownership structure that was akin to a partnership but was publicly listed. It was a useful idea-until steep declines in tax rates and energy prices put the Apache Petroleum Company to rest in 1987.

This time round the master limited partnership (MLP) structure which Apache pioneered is no longer just a footnote. In the 2000s such companies allowed the capital-intensive energy industry to attract vital funds even during a devastating financial crisis. Kinder Morgan, a complex entity built around interlocking MLPs, has an enterprise value (its market capitalisation plus its debt) of $109 billion. The collective market capitalisation of MLPs recently passed that of Exxon Mobil, the most highly valued energy company on the New York Stock Exchange.

The new popularity of the MLP is part of a larger shift in the way businesses structure themselves that is changing how American capitalism works. The essence is a move towards […]