WPP, the FTSE 100 advertising and marketing group led by chief executive Sir Martin Sorrell, has agreed to purchase a large stake in South African consultancy Arcay Communications for an undisclosed sum.Through its wholly-owned PR and public affairs subsidiary, Burson-Marsteller, WPP announced that it will acquire "a majority stake" in the firm, whose clients include BHP Billiton, Danone, Discovery, Hewlett-Packard and McDonald's.Arcay, which has been an affiliate partner in Africa with Burson-Marsteller for four years, generated gross revenues of 15.6m South African rand (ZAR) in the year to 31 March, and had gross assets of ZAR8.7m by the end of that year.The purchase will looks to develop WPP's fast-growing African businesses, where it currently employs 20,000 people and generates revenues of $500m."This acquisition continues WPP's strategy of investing in important markets and sectors," the firm said.BC