Viacom shares fell as much as 20 per cent on another dark day for US media companies as the owner of Comedy Central, MTV and Paramount Pictures hit earnings forecasts but missed estimates on revenues.

The media sector has been in freefall since Walt Disney revised its growth outlook for its ESPN sports channel this week. The declines continued yesterday, with 21st Century Fox falling 11 per cent and AMC Networks down 12 per cent. The S&P 500 Media index fell more than 4 per cent.

Big changes in distribution and viewing habits are fuelling investor concerns as a generation of younger viewers spends less time in front of a television in favour of digital alternatives.

Netflix, the on-demand streaming service, has driven much of the change in consumption patterns. Its shares hit a high yesterday for a market capitalisation of $53.7 billion – more than the combined value of CBS and Discovery Communications and close to the market value of 21st Century Fox.

Shares in Viacom, which owns the UK’s Channel 5, are down 45 per cent over the past 12 months.– Copyright The Financial Times Limited 2015