The compensation relates to a review carried out by the Australian Securities & Investments Commission (Asic), called Report 515.
In addition to reviewing the effectiveness of adviser oversight, the project reported on work being undertaken by institutions to identify and compensate customers affected by non-compliant advice provided between 1 January 2009 and 30 June 2015.
Report 515 reviewed advice compliance at insurer AMP, ANZ Bank, the Commonwealth Bank of Australia (CBA), National Australia Bank (NAB) and Westpac.
The additional A$21.4m brings the overall total of compensation paid to customers, from matters raised by the review, to A$51.4m.
Asic has now launched a major public inquiry into alleged misconduct in the banking, superannuation and financial services sector.
Australia also recently set up a financial complaints authority to deal with dispute resolutions.
Thousands affected
According to Report 515, about A$30m had been paid by December 2016 to approximately 1,347 customers who had suffered loss as a result of advice failings by 97 high-risk advisers.
The institutions have since made the additional A$21.4m in payments to more than 1,687 customers.
Asic said it expects further compensation to be paid but the amount and the number of potentially affected customers is not known at this stage.
The table below shows the updated figures.
