However Google continues to dominate – and has extended its lead – with $31.4 billion of digital media revenue for the first half of 2014 (a 12% year-on-year increase). Amazon is in second place with revenues of $10.3bn.

Facebook is third with $5.4bn (up 66%), narrowly ahead of Chinese internet service portal Tencent at $5.4bn (up 43%). Web services company Baidu ($3.4bn, up 56%) is the other Chinese firm in the world’s top six, behind Apple’s iTunes ($5.2bn).

Yahoo is the only one of the world’s top 10 to see digital media revenues decline year-on-year (down 3%).

Global research and advisory firm Strategy Analytics is behind the Digital Media Index which analyses revenue trends across 44 public digital media companies. Between them, the 44 companies generated $85.9bn in digital media revenues in the first half of 2014 – 17% more than the same period in 2013. Among the 44, Chinese internet security software firm Qihoo saw the largest year-on-year rise in revenues (up 123% to $582 million), just ahead of Twitter (up 122% to $562m). Facebook (up 66%) grew third fastest.

Alongside Baidu and Tencent, online media company Sina (up 36%) is the fourth Chinese company among the 10 fastest-growers.

Michael Goodman, director, digital media for Strategy Analytics said: “A red-hot Chinese internet market is challenging the historical dominance of US companies. The fact that there are about 2.5 times more Chinese than Americans online is a big factor so they’ve been able to hit such heights solely in a domestic market. The big question, and the key threat to US global dominance, is whether they can translate this success outside China.”