E-mail marketing firm Silverpop bought British interactive agency Digital Oxygen.
The acquisition comes a month after Silverpop opened its London office. Terms were not disclosed.
Digital Oxygen was a former client of Silverpop. Both companies held that relationship for two years before the purchase of Digital Oxygen.
Digital Oxygen clients include Midway Games, Zenith Optimedia, Proximity London, HMV and The British Horseracing Board. Silverpop, whose London office will house Digital Oxygen's staff, has clients like Gizmondo, Skype and BSkyB.