The Daily Mail reported on Friday that rumors were rife that WPP, the world's largest advertising group, is lining up a $25-a-share cash offer for the U.S. group. Interpublic's shares closed on Thursday at a little more than $17.
"We strongly refute this report," a WPP spokesman said on Friday. "It is completely inaccurate."
Shares in WPP were up 1.6 percent at 8.35 a.m. EST, outperforming a 0.4 percent gain by the FTSE 100 index. The shares are up nearly 4 percent since the group reported strong results in October, showing it was winning market share.
Analysts have questioned whether the British group would look to make further acquisitions after its two biggest challengers, Omnicom (OMC.N) of the U.S. and France's Publicis (PUBP.PA), announced merger plans in July.
The combined group would overtake WPP as the world's largest advertising company.
Reporting by Kate Holton; Editing by David Goodman