Roy Morgan found in a survey based on 50,000 interviews that NAB has the highest proportion of its customer’s superannuation assets with a share of 18.4 per cent.
CBA holds the second largest share with 13.2 per cent, followed by Westpac with 12 per cent, and ANZ with 10.4 per cent.
Both CBA and Westpac have made small gains in the past four years, according to the survey results, increasing their share by 0.5 per cent and 1.7 per cent respectively.
ANZ on the other hand has seen a 0.7 per cent decline and NAB a 2.1 per cent loss.
Roy Morgan said the industry funds are the major source of competition for all four big banks, holding an average of 25 per cent of all superannuation assets belonging to banking customers at the major four.
The industry fund share has increased across all four big banks in the past four years, according to the survey.
The figure currently ranges from 23.4 per cent for NAB to 28 per cent for CBA.
AMP is the largest single competitor for the major banks, holding around 6 per cent of all superannuation balances for each bank, from 5.8 per cent for NAB to 6.8 per cent for ANZ.
The survey also showed limited loyalty to the major banks, with around 10 per cent of each bank’s customer’s superannuation balances held at one of the other major banks.
This ranged from 8.7 per cent for NAB up to 11.9 per cent for ANZ.
Roy Morgan said the remainder of the balances are held by SMSFs, other retail funds and public sector funds.
Roy Morgan industry communications director Norman Morris said while the major banks have strength in their banking products, such as home loans, cards and deposits, they are facing “much stronger competition with superannuation where they are up against specialist providers”.
Mr Morris said with increasing balances likely to attract more competitors and attention on fees, performance and disclosure, “competition between banks and their specialist competitors in superannuation is likely to remain a problem for improving cross-sell in this market”.
