Initial reaction on the stock market shows investors do not believe there will be a significant impact on global advertising. In early trading the share price of WPP is no more volatile than usual, falling just 1.6% to GBP16.98 as of 9am UK time. It was a similar picture at French groups Publicis, down 1.6% to €59.41, and Havas, which is unchanged at €7.17.