It is thought agencies that work with Microsoft were notified of the news yesterday.
Microsoft has complex agency arrangements and works with various shops on different parts of its business.
Interpublic Group’s UM runs the bulk of the global media account, while Microsoft works with Starcom MediaVest Group in its largest market, the US.
MDC’s Crispin Porter & Bogusky is one of Microsoft’s lead creative agencies globally, and created the "I’m a PC" ads that ran from 2008.
WPP’s Wunderman also has substantial parts of the Microsoft business and works on creative, especially execution, including in Asia.
Publicis Groupe’s Razorfish also works on some global digital business. JWT Beijing won Microsoft’s digital business for Asia-Pacific markets including Japan, Hong Kong and China, in 2013.
A Microsoft spokeswoman said: "Microsoft doesn’t comment on rumour or speculation."
This article was first published on campaignlive.co.uk