The independent agency beat off competition from Beattie McGuinness Bungay in a pitch process through the AAR. Beta had also been involved in the review, but pulled out in April.
The site, which is expected to launch next year, will compete against the rival sites including Gocompare.com, Comparethemarket.com, Confused.com and Money-supermarket.com. It is understood that MMA intends to match the marketing investment of the leading UK sites with a budget that will exceed £20 million.
Gocompare.com was the top spender in the sector in 2010 with a £27.8 million media spend. Confused.com ranked second with a spend of £20.5 million, according to Nielsen Media Research.
Isobel declined to comment.