Interactive investor (ii), the flat fee investment platform, has completed its takeover of rival The Share Centre, creating a group with 570,000 customers.

The ii group has over £30bn in assets under administration, over 300,000 customers and more than 1m users. The Share Centre has 271,000 customers with £4.9bn in assets under administration.

Together the newly-enlarged business has assets under administration of nearly £36bn, ii says.

The merged group claims to be the UK’s 2nd largest direct to consumer investment platform and the biggest flat fee provider.

Interactive investor offers clients a flat-fee investment platform covering ISAs, SIPP, Junior ISAs and general investing accounts. Customers pay a flat monthly fee regardless of size of investment. The Share Centre’s clients will have access to the same services and tariffs.

Richard Wilson, chief executive of interactive investor, said: “I am very pleased to welcome The Share Centre to interactive investor, further strengthening the voice for flat fees.

“We want to do as much as we can to make investing simple so more people can take control of their financial future. Having permanently scrapped exit fees 2 years ago and moved to a modern monthly subscription fee last year, where customers can choose the best price plan for them, in January we were also the first major platform to make regular investing completely free.”

Gavin Oldham, executive chairman of Share plc, said: “We are delighted that  customers of The Share Centre will benefit from the combined strengths of both businesses.”