The estimated increase is set to overtake the 2.5% rise forecast for this year but is lower than the 7.3% growth recorded in 2018.

However, growth is increasingly driven by spend on Facebook, Google and Google’s YouTube, which together are expected to account for over half of all ad investment for the first time next year. Global spend is flat outside of the three.

The report predicts ad investment to increase ahead of the global rate in eight categories, with financial services leading the way with a projected 11.8% rise in spend, followed by household and domestic, transport and tourism, telecoms and utilities, tech and electronics, alcoholic drinks, automotive, and soft drinks.

All other product categories monitored by Warc are predicted to increase spend, with the sector forecast to post the lowest growth at 2.6%.

James McDonald, managing editor, Warc Data, and report author, said: "Weak macroeconomic indices, waning business confidence and rising geopolitical tensions have increased the possibility of a recession in 2020. Within this climate, our forecast of six percent growth in global advertising investment may seem optimistic, but these projections are in line with those from the IMF and Euromonitor for GDP and consumer spend, respectively."