One AMP fund and a host of smaller corporate and industry super funds are likely to come under increasing pressure to merge, restructure or close after being outed as poor performers by the financial stability regulator.

In what has been coined "D-day for dud funds", the Australia Prudential Regulatory Authority's "heatmap" analysis of the worst-performing super funds was released Tuesday. It comes amid mounting pressure for transparency in the industry that has been accused of fostering chronically defective funds with opaque fee structures and uncertain returns.

The regulator's analysis highlighted funds with dwindling member numbers and net cash outflows. AMP's NM Super was outed as the least sustainable fund with a 17.35 per cent decline in account numbers and negative cash flow of 9.66 per cent over a three years to June 30, 2019.

Other funds with questionable long-term viability include Goldman Sachs & JB Were Superannuation Fund, Toyota Super My Super Growth and Victorian Independent Schools Super Fund - Balanced Option.