The bosses of two of Australia's largest retail banks are confident about the outlook so long as the national COVID-19 recovery plan is followed and restrictions are lifted.

"The current challenges of COVID and lockdowns are significant, but I am optimistic about the nation's path forward," Westpac CEO Peter King told the House of Representatives economics committee.

National Australia Bank CEO Ross McEwan told the hearing in Canberra the current series of coronavirus lockdowns have not been as financially damaging for many of its customers as last year's national shutdown.

He said many businesses are in a state of hibernation while waiting for restrictions to open up, and ready to get going again.

"For others, in particular, small business customers in Sydney and Melbourne CBDs, the situation is more fragile," Mr McEwan told the hearing as part of the committee's regular catch-up with the big four banks.

"The number of customers in financial hardship is rising since the Delta outbreak but most continue to be able to make some form of payment."

At August 31, just over $1.8 billion in NAB lending was on deferral compared with $58 billion at the height of the pandemic last year.

Mr McEwan noted that before the most recent lockdowns, the level of small and medium business lending activity was the highest the bank had seen in six years.

"While some businesses are really hurting, others are doing incredibly well," he said.

"This is particularly evident in mining, agriculture and some forms of manufacturing."

Mr King said Westpac has $2.75 billion of mortgages with repayment deferrals compared to $55 billion at their peak.

Total deferral for small business loans is $70 million compared to a peak of $10 billion.

"Small businesses are showing particular resilience," Mr King said.

"Many have pivoted or evolved their operations and supply chains so they can better withstand lockdowns."

Mr McEwan said there is light at the end of the tunnel with forecasts that 80 per cent of eligible Australians will have had their second coronavirus vaccination by mid-November.

"When we can safely move from restrictions to freedoms, I am very confident the Australian economy will recover swiftly," Mr McEwan said.

Part of the hearing was taken up by a separate inquiry into capital concentration and common ownership in Australia, and what influence that can have on the decision making of public companies and competition

Mr McEwan said he doesn't have concerns at this point in time, but noted over the next 30 to 40 years the amount of capital coming through super funds will nearly double.

"So this is a large amount of money coming from these super funds and into organisations such as ours and broadly across the ASX," he said

"I don't have concerns based on what we have experienced to date because they haven't interfered, or tried to interfere, in the running of polices of this bank."

Mr King denied it was the influence of the super funds that saw his predecessor Brian Hartzer dismissed, but rather a decision of the Westpac board after taking account views of all shareholders.

The ANZ and the Commonwealth Bank will be grilled by the committee on September 23.