The original company, founded in 1919, separated its international operations into a separate traded company on December 1, 1964. Subsequently, Trans World Corp., the holding company for Trans World Airlines, acquired Hilton International Co. in 1967. In 1986, UAL Corp., the holding company for United Airlines acquired Hilton International Co. from Trans World and changed its name to Allegis Corp. as it attempted to re-incarnate itself as a full service travel company encompassing Westin Hotels and Hertz rental cars in addition to Hilton International and United. In 1987 after a corporate putsch, the newly renamed UAL Corp. sold Hilton International to Ladbroke Group, a British leisure and gambling company, which in May 1999 adopted the new moniker Hilton Group plc.
As a result, there have been two separate, fully independent companies operating hotels under the Hilton name. Those Hiltons outside the US were, until recently, styled as Hilton International hotels. In addition, for many years hotels run by the Hilton Group in the US were called Vista International Hotels, while hotels operated by the American arm of Hilton outside the US were named Conrad Hotels. The Vista chain has been phased out, while Conrad is now restyled as the luxury brand of Hilton and operates hotels within the US, as well as abroad. To minimize consumer confusion, the American and British Hilton companies have, for the last few years, had a joint marketing agreement under which they share the same logos, promote each other's brands and maintained joint reservation systems.
On December 29, 2005 Hilton Hotels Corporation agreed to re-acquire Hilton International along with its Conrad Hotels, Scandic Hotels and LivingWell Health Clubs affiliates from British-based Hilton Group (FTSE:HG) for GBP 3.30 billion (or $5.71 billion) bringing the two groups back together.
The Waldorf=Astoria Collection was announced on January 17, 2005 as a new Luxury Brand.