The Internet will be the biggest advertising medium in 12 key markets such as China, India and Indonesia, which will together represent 28% of global ad spend by 2017, according to ZenithOptimedia.
The company forecasts that in four of these markets, Internet advertising will attract more than half of total ad spend.
Globally, the internet will remain in second place, behind television, though the gap between the market shares of the two media will shrink from 11 percentage points this year to just four percentage points in 2017.
The Internet was already the dominant medium in seven markets – Australia, Canada, Denmark, Netherlands, Norway, Sweden and the United Kingdom – last year, and by 2017 will dominate another five – China, Finland, Germany, Ireland and New Zealand.
Also, the Internet’s market share will exceed half of ad markets in the UK this year, in Denmark and Sweden next year, and in China in 2017.
The main driver of Internet growth is mobile advertising. ZenithOptimedia forecasts that between 2014 and 2017, mobile will more than double its share of global ad spend, from 5.1% to 12.9%.
Mobile is also driving the growth of the whole market, and will contribute 70% of all global ad spend growth between 2014 and 2017.
ZenithOptimedia forecasts that global ad spend will grow 4.2% to reach $531 billion in 2015, and will accelerate to 5% growth in 2016, boosted by the 2016 Summer Olympics in Rio and the United States presidential elections.
Ad spend will then slow down slightly in the absence of these events, growing 4.3% in 2017.