LONDON: A proposed merger between market research giants Taylor Nelson Sofres and GfK, unveiled last week, has brought forth an expected acquisition bid by advertising conglomerate WPP Group.

However, the £948 million ($1.87bn; £1.2bn) offer has been swiftly rejected by the TNS board on the grounds that it undervalues the UK-headquartered company.

UK-based WPP has responded by saying: "We think the response is cavalier, given the proposal was made only a day or so ago and offered shareholders a significant premium."

The putative merger has also triggered speculation that the world's number one market research firm, The Nielsen Company could make a bid for German-headquartered GfK, but the latter says it has had no approaches.

Data sourced from Financial Times Online; additional content by WARC staff