Like many big media families, the Texan Mays clan has dealt with its fair share of political controversy. Founded in 1972 by Lowry Mays, the company’s chairman, his two sons Mark and Randall now run Clear Channel and they will continue at its helm following the buyout.

As the biggest radio broadcaster in the US - and the world - stock markets were for years enamoured with the group’s ability to turn flagging radio stations into profitable businesses, and this fuelled an acquisitions frenzy which turned Clear Channel into a media giant.

Retaining its base in San Antonio, Texas, a change in regulation in 1996 allowed Clear Channel to sweep up more stations. The company now has more than 1,200 stations and owns a substantial number of billboards and other outdoor advertising assets as well as some television groups.

The shift of audiences and advertisers to other media such as the internet, and listener frustration with the large number of commercials included on ad-funded radio stations, led to declines in growth and a downward revision of Clear Channel’s prospects by Wall Street.

The loudest public criticism has been about Clear Channel’s degree of radio control and its standardisation of radio formats. The group was accused of overplaying hit songs. Other controversies have included increasing the prominence of shows for political reasons, such as that of rightwing talk show host Rush Limbaugh.

Mark Mays has spearheaded a plan to make radio more appealing, with the length of commercials and the number of ads recently slashed.