The agency says the revision was caused by the noticeable slowdown in economic growth and continued economic uncertainty in Europe and the US, as well as the cautionary marketing spend seen in the second half of this year.

Magna’s figures reveal that the global advertising market reached $495bn this year, up 3.8% on 2011. The US remains the largest market with $153bn in advertising revenues. Japan, China, Germany and the UK complete the top five.

The US ad market grew by 4% in 2012, in great part thanks to the influx of political and Olympic-based ad campaigns. However, Magna warns that without any such drivers next year, and with 2012 being a hard act to follow, US ad revenue in 2013 will see growth of just 0.6%.

In Western Europe, meanwhile – and despite modest growth in the UK and Germany – Magna says ad revenues decreased 2.8% in 2012, and it expects 2013 to be down 0.1%. Southern Europe will decline by 4.3% but central and eastern Europe will grow by 7%, Latin America by 11.9% and Asia-Pacific by 4.8%.