The boss of Australia's largest bank admits it has failed to prevent misconduct and ended up in an increasing cycle of compensating customers without fixing the problems.

Commonwealth Bank of Australia CEO Matt Comyn says the bank has not consistently prioritised customers' interests, leading to decisions that resulted in financial gain at their expense.

Mr Comyn said the bank has been unable to prevent misconduct and immediately identify, resolve and remediate misconduct when it occurred.

CBA has been caught in an escalating cycle of funding remediation, resolution and rectification rather than prevention and simplification of systems and processes, he told the banking royal commission.

"We seemed to be caught reacting, responding, remediation, in an ever-increasing cycle of that without actually truly understanding the root cause, making the appropriate investments to actually prevent issues from recurring," he said on Monday.

Mr Comyn also admitted CBA had not learnt from past mistakes.

"Ultimately that's why I say we get into a period of ongoing remediation without actually fundamentally understanding the root cause in each of those matters and making demonstrable steps to ensure they don't recur."

Mr Comyn said CBA has been insular and complacent.

He also called out the bank's problematic relationships with regulators, saying it had been defensive and legalistic in its dealings with them.

The one thing Mr Comyn, as the first bank CEO to front the inquiry's final hearing, did not do on Monday is apologise.

Senior counsel assisting the commission Rowena Orr QC had warned the inquiry did not want to hear any more apologies from entities involved in misconduct.

"The purpose of this round of hearings is not to hear further apologies, or expressions of regret," she said.

She said the inquiry will focus on why misconduct occurred and what can be done to prevent it in the future.