AppNexus has acquired MediaGlu, a company which specialises in cross-device mapping.

By integrating MediaGlus probabilistic technology into its platform, AppNexus intends to help advertisers track users and attribute results across desktop and mobile.

The terms of the deal are undisclosed, though Forbes reports that AppNexus has spent a combined $200m in 2014 on three acquisitions.

In June, AppNexus bought French ad viewability solutions company Alenty. This was followed in September by the acquisiton of Open AdStream, formerly known as Xaxis For Publishers, the biggest of the deals.

“AppNexus is dedicated to creating a better internet, and engaging with consumers across devices provides a more relevant and consistent experience for advertisers, publishers and end-users alike,” said Jonathan Hsu, CFO and COO of AppNexus.

“MediaGlu’s technology will be a key component of our platform moving forward, and its elite team of experts will greatly advance our progress in the mobile space. This acquisition caps a year of robust growth at AppNexus, a pattern that we fully expect to see continue in 2015.”

MediaGlu will wind down its media business to concentrate exclusively on development of its technology, with the six-person team remaining in their current headquarters in Baltimore.