Pharma giant Pfizer is conducting a media agency review, according to sources.
The company spent $1.3 billion on ads in 2009, and $600 million during the first six months of this year, according to Nielsen.
The incumbent is Aegis Group's Carat. It was not immediately clear if the shop is defending.
Neither the client nor the agency responded to queries about the review.
The review marks the second big pharma reassessment in as many weeks, following on the heels of the GlaxoSmithKline competition. GSK's media incumbent is MediaCom, which is planning to defend, sources said.
Earlier this month, Pfizer shifted lead creative duties on its Advil brand to mcgarrybowen after a review. The Dentsu-owned shop will handle Advil, Advil PM and Children's Advil, as well as ThermaCare, another Pfizer brand.
Earlier this year, Carat was awarded duties on Pfizer's recently acquired Wyeth brand.
It's been a hectic year for Carat in terms of new-business activity, and losing Pfizer would be a major blow.
Its losses include RadioShack, Alberto Culver and Revlon, worth about $350 million in combined overall media spending.
On the plus side, along with the $250 million Wyeth business, Carat has added Smucker ($125 million), Beiersdorf ($100 million) and Red Bull ($50 million).