Media tycoon Richard Desmond is considering selling Channel 5, for several times his original investment.
Mr Desmond bought the broadcaster for £103.5 million in 2010 and, according to reports, is hoping the channel will now fetch £700 million.
The media tycoon, who also owns the Express and Star newspapers, has appointed Barclays to handle the sale.
Several corporations are likely to be interested in buying the channel, including ITV and the American network Turner Broadcasting.
Some experts are expecting the terrestrial broadcaster to spark the interest of pay-TV rivals BT and BSkyB.
Thomas Singlehurst, head of European media equity research at Citigroup, said: "It is a really big deal, a fascinating potential transaction because there could be a decent amount of interest from BT and BSkyB for a load of offensive and defensive reasons."
Mr Desmond has helped transform the channel with new executives and popular programmes like Big Brother, which it bought from Channel 4.
In the first half of 2013 Channel 5 made profits of £20.6 million, compared with a £16.1 million loss a year earlier.
The broadcaster has also managed to maintain steady viewing figures.