Aegis, which owns media-planning and buying network Carat, saw its share price jump sharply this morning, up 6% to 114.5p from last night's close of 108p.
An Aegis spokesman said the group was not in talks with anyone. The denial follows the statement this morning from Tempus that it has held talks with WPP.
WPP is believed to be close to launching a £450m bid for Tempus and possibly spark a bidding war with Havas, which has bid £425m.
Aegis and Tempus have long been seen as takeover targets. In June, WPP was understood to be pursuing a share-swap deal which would have seen it swap its stake in Tempus for a stake in larger rival Aegis.
WPP owns 22% of Tempus and had proposed to swap its holding for a 5% stake in Aegis, which is valued at £1.3bn compared with Tempus's £332m.
Aegis shares have had a bumpy ride this year. In July, Aegis saw its shares fall 26%, wiping more than a quarter off of its value as it reported worsening marketing conditions. The FTSE-250 company saw its shares hit a new low of 79p, down from 108p. The share price was the lowest the shares had been at since 1998.