Drawbridge, the desktop-to-mobile retargeting start-up founded by a former Admob employee, has raised $14m (£9.2m) in Series B funding to support its product development.

The first ‘self-learning’ ad platform says it has already matched 450m computer owners with their handheld device, growing by 4m every day. This enables the company to extend desktop ad segments to mobile campaigns and retarget people as they move from one device to another.

Northgate Capital, a new investor, led the round, and was joined by previous funders Kleiner Perkins Caufield and Byers and Sequoia Capital. As well as investing in its retargeting tech, the company will use the money to accurately track conversions, optimise post-conversion and expand the sales and marketing team.

Dr Kamakshi Sivaramakrishnan, who studied information theory at Stanford University before working in optimisation and targeting at AdMob, founded Drawbridge in November 2010. The company raised $6.5m in its Series A round in May of 2012.

Using machine learning algorithms, Drawbridge says it is solving one of the primary problems in digital advertising: enabling anonymous, cross-device user identification.