The news lifted Tempus shares in early trading as much as 14.3% to 500p before they dropped back slightly to 492.5p. At the same time WPP said it had extended its deadline for acceptances until October 15.
Tempus shares have risen a long way from yesterday's depressed opening of 437p, but they are still considerably short of WPP's 555p per share offer. WPP shares were trading this morning at 464p - down 3.93%.
French group Havas Advertising withdrew its offer as share prices collapsed on September 21 after the terror attacks in America. Its withdrawal left WPP's offer as the only one on the table.
WPP's bid values Tempus at £432m - far above Tempus' current, post-collapse value of just £356m.
Sir Martin Sorrell, WPP's CEO, is now legally obliged to go ahead with the offer unless he can find a loophole in the deal.
This is obviously on Sir Martin's mind as significantly, the WPP said the takeover was still subject to a "no material adverse change" condition, which could be a possible way out of the deal.
There has been some speculation that WPP will appeal to the City regulator, The Takeover Panel, and ask for the deal to be scrapped on the grounds that the global economy has suffered a radical and unprecedented crisis since the offer was launched.
However, WPP might well find this position difficult to argue as it upped its stake in Tempus to 26% after the World Trade Centre attacks. The group already owned 22% of Tempus, which it bought earlier this year at an average price of 220p. The additional shares were bought at 555p a share.
Tempus' management has already has recommended WPP's offer. They made their recommendation immediately following Havas' dramatic withdrawal from the race for the CIA-owning media group.
Last week Tempus reported its half-year pre-tax profits down 16% to £8.9m as a result of waning confidence in the media sector.
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