LONDON: WPP Group has extended the deadline for acceptance of its bid for Taylor Nelson Sofres until September 26. Just 11% of the UK-headquartered research giant's shareholders have so far said yes to Sir Martin Sorrell's $2.2 billion (€1.5bn; £1.2bn) offer.

TNS has again urged investors to reject the bid, believing the WPP ceo may dig deeper into his  pockets if they hold out a little longer.

The firm's chairman, Donald Brydon, reportedly met with Sorrell last week to discuss the possibility of a revised offer.

However, in a statement, TNS said it was "disappointed that WPP has declined to enter into a dialogue with TNS regarding the benefits of a recommendation [to] . . . commit to cooperate with WPP to ensure a successful transition to WPP ownership".

Data sourced from Adweek (USA); additional content by WARC staff