Omnicom Group is in advanced talks to acquire Interpublic Group, according to The Wall Street Journal, which published a story about the development today. 

The Journal cited anonymous sources and reported that a deal might be announced sometime this week. 

Representatives from Omnicom and Interpublic did not return queries seeking comment by the time of this posting. 

If a deal is reached, the combination would create the largest ad marketing group by revenue, per the Journal, which reported that an all-stock transaction was being discussed which would value IPG at between $13 billion and $14 billion. The company’s market value was about $11 billion at the end of Friday’s trading session. 

Through 2023, WPP was the largest holding company by net revenue followed by Publicis, Omnicom and Interpublic. 

If Omnicom and IPG complete a deal, the combined companies would have revenue of close to $26 billion.

Omnicom owns agencies such as OMD, PHD on the media side and DDB and TBWA on the creative side. Earlier this year it made its largest acquisition in its history with the purchase of commerce company Flywheel Digital for $835 million. 

Omnicom was involved in the last proposed megamerger among holding groups, in 2013 when it struck a deal to merge with Publicis Groupe. That so-called "merger of equals" fell apart in 2014.

Interpublic owns media agencies UM, Initiative and Mediahub and creative agencies FCB, McCann and Mullen Lowe among others. 

The reported talks follow word last week that IPG sold digital agency Huge to investment firm AEA while acquiring commerce platform Intelligence Node.