WPP, hunting for a new chief executive after the dramatic departure of founder Martin Sorrell in April, had reported a 0.1 percent fall in net sales for the first quarter, compared with the 0.9 percent drop recorded in 2017.

"In the first four months of 2018, the group's like-for-like revenue less pass-through costs was up marginally, a slight improvement over the first quarter's -0.1 percent," WPP said in a trading statement before its annual meeting on Wednesday.

For 2018 it has said it does not expect net sales or its operating margin to grow.

(Reporting by Sarah Young and Kate Holton; Editing by Alistair Smout)