With the offer document out, a timetable is now in place for the deal to be completed by August 20.
Executives at the two firms are hoping that at least 50% of shareholders will accept the premium offer, which has continued to fuel Tempus's share price.
This morning, the share price is up at 564.5p, having soared from 360p two weeks ago when the deal was first announced.
Shareholders will be waiting to see if a counter-bid from Sir Martin Sorrell's WPP Group emerges. WPP owns a hefty 22% stake in Tempus and is known not to want to see the group fall into the hands of a rival.
Havas and Tempus plan to merge their media-buying arms, Media Planning and CIA respectively, to form CIA Media Planning.
WPP executives are currently examining Tempus's financial data before making a move.
Some in the industry have poured cold water on the possibility of a WPP bid for Tempus, as it is well known that the management is hostile to a WPP takeover.
Chris Ingram, the Tempus CEO who owns 16% of the firm, is well known to be anti-Sorrell. Some weekend reports indicated that all of the senior management is against a WPP deal, but this is not believed to be the case.
This article was first published on brandrepublic.com