As a result of the deal, the founders have been paid an aggregate cash payment of €1.12m (£901,232) and have resigned as directors, including the president director of Directinet, who has been paid €200,000.
IPT Holdings has appointed one its own founders, Martin Kiersnowski, as chairman of Directinet, and consultant John Lloyd as interim chief executive, until it finds a permanent candidate for the role.
Kiersnowski has 30 years' experience in direct marketing and has recently been working for IPT's French subsidiaries. Lloyd has worked as an accountant and expert in turning around companies and as a consultant to IPT Holdings since July.
Nicholas Ward, IPT Holdings chairman, said: "We now have full management control of our largest subsidiary, which is a profitable and cash-generative business and which is trading in line with budget.
"This is a significant further step forward in implementing the outcome of the strategic review."
The strategic review at the online marketing group this week saw it offload two of its market research businesses, RWCEL and Integra Insight. At the beginning of October it sold a number of businesses, including Interactive Prospect Targeting, to venture capital firm Volvere for £1.3m in cash.