Under the agreement, Aegis will acquire Bluestreak's proprietary ad-serving technology, a hosted online advertising suite that helps advertisers to manage and execute campaigns across all online media.
The Bluestreak system helps advertisers to understand how clicks translate into purchases and revenue.
In 1999 Aegis and Bluestreak, which specialises in the delivery of rich media, collaborated on the first US rich media advert for Pfizer's Zithromax, an antibiotic drug.
Bluestreak's ad-serving employees will be transferred into Isobar, Aegis Group's digital agency network. The two businesses already have a search partnership in place, with Bluestreak fully integrated into Isobar's paid search bidding agent iSEBA.
Isobar will integrate Bluestreak data with its existing online media services to form a new digital data capability, offering global reporting of data across search and display.
Aegis chief executive Robert Levill heralded the acquisition as a "landmark deal" which will have "multiple future applications across our entire group".
Bluestreak was set up in 1999 and is one of a handful of established international ad-serving businesses worldwide, active in the US, UK, France and Germany.