WPP, one of the world's largest advertising groups, has announced it intends to invest in Polestar, a start-up Chinese e-commerce service company that has partnerships with Chinese and international brands.WPP will take a minority stake in Polestar, which will be led by its principal investors, many of whom used to work for Alibaba."Understanding and monetizing the e-commerce opportunity is a top priority for all brands in China, and by partnering with Polestar we can now offer our clients a one-stop solution, a first in China," said WPP chief executive Sir Martin Sorrell.Polestar was formed from a merger of five third-party service companies in April and while the value of WPP's investment was not disclosed it is thought to be a multi-million-dollar sum.Led by Alibaba, China's e-commerce market is the world's largest, having surpassed the US in 2013, and Chinese online shoppers are expected to spend RMB3.3trn ($540bn) next year."We are delighted to work with WPP and its agencies, and to help their clients become e-commerce leaders in China," said founder Figo Yang, chief executive of the venture.