Advice business St. James’s Place lays claim to 12 per cent of UK adviser sales based on its most recent financial data.
According to a report by analysis firm Plimsol, SJP topped the group of advisers with the largest marketshare by a margin of 6 percentage points.
The data showed SJP made £893.1m in sales in the year 2017/18, based on its latest financial results.
Towers Watson was reported to have made 6 per cent of all sales while Brewin Dolphin Holdings had the third largest marketshare, at 4 per cent.
Towers Watson and Brewin Dolphin were reported to have made £447.7m and £304.5m in sales respectively.
Collectively, the biggest advice firms are on the road to market dominance, the report showed.
The top 25 firms claimed a marketshare of 48 per cent of sales in the last year and experienced an average 12 per cent growth, compared with the market average of eight per cent.
Martin Bamford, financial planner and managing director at Informed Choice, said the increased growth of larger firms could have a negative impact on the market.
He said: "The growth in market share of the biggest firms has grown and this is likely to stay the same. A large factor in the growth is likely to be the amount of acquisitions of smaller advice firms, carried out by bigger player.
"We are likely to see more big consolidators in the marketplace snapping up smaller firms, ultimately this will be detrimental to competition and quality of advice."
FTAdviser recently reported that SJP would be further investing in its discretionary fund management (DFM) arm in order to grow the business beyond its current reach. Its DFM arm was reported to have client assets of £2.3bn at the end of 2017.
In July this year, SJP announced it would be launching its Diversified Assets fund to allow clients to invest in assets that had previously only been institutional investors, as a way of assessing its client offering.
Scott Gallacher, financial planner at Rowley Turton, said SJP's proportion of market share was unsurprising.
He said: "The 12 per cent figure on its own doesn't alarm me in terms of dominance of the market.
"For all of SJP's sins, the profession needs some large players to invest in new advisers which SJP does do via its academy."