Marketing firm WPP agreed on Monday to invest $25m in Microsoft-backed adtech firm AppNexus, increasing its stake from less than 1% to almost 15%, according to the Wall Street Journal.
US-based AppNexus is a publisher ad server platform that allows real-time buying and selling of digital advertising. It raised $60m in series E funding last month at a $1.2bn valuation.
AppNexus’ backers also include venture capital firms Technology Crossover Ventures, Venrock, Kodiak Venture Partners, Tribeca Venture Partners, First Round Capital and Khosla Ventures.
WPP paid a relatively low price for the stake because the deal includes the transfer of Xaxis for Publishers software held by WPP subsidiary Xaxis to AppNexus. The software programmatically connects advertisers and publishers to audiences across different channels.