French advertising agency Publicis Groupe is weighing a bid for US rival Interpublic Group, said a report by FT Alphaville yesterday, sending Interpublic’s stock sharply higher.

Publicis is weighing a bid that could be worth at least $6 billion, FT Alphaville said, quoting “usually knowledgeable” sources yesterday.

An equity valuation at that level would represent a premium of over 40 percent to Interpublic’s market value on Thursday.

Shares of Interpublic closed up 13 percent at $10.97 yesterday on the New York Stock Exchange.

“We are aware of the activity in our [shares]. It is our policy not to comment on market rumors or speculation,” Interpublic said in a statement yesterday.