Microsoft’s share of revenues across three screens has dropped from around 58 per cent in 2008 to less than 30 per cent in 2013, while Apple’s share has risen from just over 20 per cent to 56 per cent today.

Although Microsoft’s desktop revenue grew above $15bn in 2013, greater than in 2008 and 2010, Apple’s combined ‘post-PC revenue’ plus desktop exceeds $50bn, while total revenues at Microsoft are closer to $20bn.

Steve Ballmer, who has been CEO of Microsoft since 2000, has announced today that he will retire within the next year. The company has struggled to reinvent itself to compete in the tablet and smartphone markets.

The revenue shares of the three largest hardware and software ecosystems have been compared by analyst Chetan Sharma as part of his report series Mobile Fourth Wave: Evolution of the Next $1trn. Google’s revenue share has stayed consistently around 20 per cent for the last five years.

Commenting on the post-PC shift, Sharma said: “While the progress of the past 20 years has been phenomenal, the connect and mobilise everything characteristic of the next revenue curve is going to define the industry itself while determining the new winner and losers for consumers mindshare.”

For the full Chetan Sharma report, which examines how various players across the ecosystem are adapting, click here.