Financial terms of the deal, which awaits regulatory approval, have not been disclosed but an SSI spokesperson described it as a “combination of equals”.

The two companies will come together under the SSI brand, with SSI’s CEO Kees de Jong (pictured) continuing as CEO of the new business. David Haynes, CEO of Opinionology, will serve as president and chief operating officer.

Charles Gottdiener of Providence Equity Partners, which owns the majority of SSI, will serve as chairman, while SSI’s current chairman Simon Chadwick will keep a seat on the board and “play an active role guiding the new company”. Sterling Investment Partners, which owns Opinionology, will also be represented on the board.

The combined company will have 1,300 employees in thirty offices around the world.

“By uniting two global leaders we will provide an unprecedented level of support,” said de Jong.

David Haynes said: “As a unified entity, we will have even greater resources to support continued investment in product innovation, technology advnaces and process improvements, ensuring we create the next generation services to meet our clients’ changing research needs.”

From the point of view of panel members, the companies’ panels will retain their current branding.

Opinionology, previously Western Wats, has only had its current name for seven months, having rebranded in November last year.