Brothers David and Charles Koch together own most of Koch Industries -- the second largest privately owned company in America, and what David Koch calls 'the largest company that you've never heard of.' Together, they are spending hundreds of millions of dollars waging a highly organised -- and often secretive -- campaign against progressive politics in the US. They've bankrolled campaigns against healthcare reform and for climate change denial, and have strong connections with the Tea Party. For people in the know, their vast right-wing network is referred to as the Koctopus.

Lee Fang has been researching them for several years.