Koch is the billionaire co-owner and CEO of Koch Industries (oil, chemicals, energy, minerals, fertilizers, finance, ranching etc.), the second largest privately held company in the US.
Homes - Celebrity - Business
As of August 2014, Forbes estimates his net worth at ~ $42 billion, making him the sixth-richest person in the world.
He purchased this 6,000 sqft Aspen home in 1992 for $2.65 million.