Media giant WPP, run by Si Martin Sorrell, has bought Chilean consumer insight group Cadem Advertising in an effort to expand its footprint in fast-growing markets.Cadem, acquired by WPP's brand, media and communications research subsidiary Millward Brown, was founded in 1997 and has served clients including Coca-Cola, Falabella Retail, Nestle, Telefonica and Unilever.The firm has operated as a licensee of Millward Brown for many years providing brand tracking, quantitative and qualitative research services."This acquisition continues WPP's strategy of investing in fast growing markets and sectors and its commitment to developing its strategic networks throughout Latin America," WPP said.Cadem generated 3.2bn Chilean pesos (around £4.2m) in revenue in 2011. WPP's annual revenues in Latin America total around $1.5bn.By 15:15 on Friday, WPP was trading 0.18% higher at 821p.BC