The pitch was for the consolidated media planning and buying account after spread-betting company City Index acquired IFX-owned Finspreads last month.
The Gate, which has held the City account for two-and-a-half years, pitched against Finspreads' incumbent agency Ptarmigan Media.
The brief covers City Index's regions across the UK, Asia and USA, with the media strategy to focus mainly online with additional spend on taxi, Underground and print, as well as direct mail.
The aim is to drive customer retention and encourage fresh switchers from spread-betting competitors. Spread betting is a method of trading on specific stocks and futures markets.
It is an area that is growing rapidly, with an estimated 100,000 or more people in the UK either spread betting or trading spread-bet contracts.