Bayer announced that it will split global advertising duties between Omnicom and WPP, a consolidation process set to be completed over the next two years.

Account duties at WPP will be shared between Ogilvy & Mather and JWT. At Omnicom, BBDO Worldwide and CDM will serve as lead agencies, according to an emailed statement from Bayer.

The consolidation will affect around 50 of Bayer’s healthcare brands. On the media buying and planning side, Bayer will consolidate all global accounts outside of the US with WPP’s GroupM (which includes Maxus, Mediacom, Mediaedge:cia and Mindshare). Media assignments in the US were not affected; Bayer consolidated US media with Interpublic Group’s Initiative agency last November.

Bayer Healthcare CEO Arthur Higgens said in the statement that Bayer hopes the consolidation will save the company as much as 10% in expenditures. Advertising Age put the total value of Bayer’s healthcare advertising account at $850 million.

Bayer’s Healthcare business, which includes pharmaceuticals, OTC drugs, animal health products and other consumer goods, had sales of just over $16 billion for the first nine months of 2009, according to third quarter reports. Despite some friction with DDMAC last year, Bayer’s blockbuster birth control pill Yaz remains the company’s best-selling pharmaceutical, at $1.3 billion for the first nine months of 2009.