The advertising downturn will worsen in the US next year, according to the latest forecasts from Group M, defying more optimistic forecasts that the media sector could recover next year.

Group M, the world’s largest media agency, on Tuesday cut its forecast for global advertising spending to $425bn this year. This would mark a 4.4 per cent decline from the previous year, against its original forecast of a 0.2 per cent decline. The market grew 3 per cent last year.