StrikeAd, a startup that helps advertisers and agencies manage their mobile campaigns, has raised another $500,000 in funding.

The round is an addition to the $3 million Series A led by DFJ Esprit that the startup announced in January. More impressive than the amount of funding is who it’s coming from — Jeff Clavier’s firm SoftTech VC, Siemer Ventures, and Applied Semantics co-founder Gil Elbaz (he’s now CEO of Factual).

By bringing on three West Coast investors, StrikeAd is also signaling its US ambitions. The company has moved its headquarters from London to New York City (specifically to Fifth Avenue in the FlatIron district). Founder and CEO Alex Rahaman has made the move, too.

Founded in 2010, StrikeAd bills itself as the first demand-side platform (an important technology in the desktop advertising world for managing multiple campaigns and multiple ad exchanges) for mobile.

“Mobile advertising is still in its infancy, and it is critical that brands and agencies leverage elite services likeStrikeAd’s to optimize their ad placement and targeting by reaching consumers with the most relevant content possible,” Clavier said in the announcement.

StrikeAd also raised an $800,000 seed round from Thomas Falk (eValue Group).