WPP contributed $25m to the round, which supported the acquisition of its subsidiary OAS by AppNexus.

AppNexus, a US-based provider of technology for internet advertising marketplaces, closed a $110m series E round yesterday, which included a $25m investment by marketing firm WPP.

WPP paid $25m earlier in September to reportedly increase its stake in the company from 1% to 15% as part of a deal that also included the transfer of advertising service platform OAS, formerly known as Xavis for Publishers, to AppNexus.

The round was led by an investor AppNexus described as a “large,…