The leading fractional aircraft ownership company, NetJets operates about 870 planes co-owned by its clients, who are guaranteed a specified model of aircraft within a few hours' notice. NetJets offers its services in the US, Europe, and the Middle East. Along with flying the aircraft, NetJets arranges a variety of travel-related services, from catering to emergency medical treatment. In addition to the fractional-ownership fleet, NetJets manages about 170 planes on behalf of individual owners. Billionaire investor Warren Buffett's Berkshire Hathaway owns NetJets, which was founded in 1964 as a charter company, Executive Jet, and later introduced the concept of fractional ownership of aircraft.