A deal has yet to be completed, although it is understood that Grey is looking to buy all remaining shares in the well-regarded 22-year old agency.
Mike Amour, chairman and CEO of Grey Asia-Pacific, did not comment on the deal, but said: "Campaigns & Grey has, and continues to be, Grey Group's valued partner in the Philippines. Beyond that, we expect to continue a fruitful relationship long into the future."
Campaigns has been minority-owned by Grey since 1996, when Grey succeeded Interpublic Group as the company's multinational partner.
However, since the acquisition of Grey Global by WPP in 2004, and the subsequent shift of MediaCom, Grey's media arm, into GroupM, Grey has been free to acquire the remaining stake in Campaigns.
Previously, foreign ownership laws drafted under the rule of former dictator Ferdinand Marcos prevented multinationals from wholly owning local media companies in the Philippines.
Campaigns launched in 1986, and now counts GlaxoSmithKline, Ford, Boehringer Ingelheim, Axa and P&G as its key clients.
Campaigns & Grey general manager and COO Marilyn Villapando was unavailable for comment as Media went to press.