This follows STW shareholder approval at a general meeting held yesterday.

The merger was originally announced in December of last year, and at yesterday's meeting STW shareholders voted in favour of all resolutions associated with the transaction, which will see WPP become the majority shareholder of STW and STW become the primary vehicle for WPP in Australia and New Zealand. 

The combined entity will be known as WPP AUNZ.

"We are delighted that the merger with the WPP Australian and New Zealand businesses has received such a positive endorsement today from the STW shareholders," said WPP AUNZ chairman Robert Mactier.

"It indeed heralds a new and exciting era which will be very exciting for STW shareholders, WPP, our collective clients and all of the very talented people across the merged group."