Ralph Norris will step down as CEO of Australia's key financial institutions Commonwealth Bank in November and he will be replaced by Ian Narev.

Commonwealth Bank said in an issued statement that Mr Norris will retire in the fourth quarter and recently-appointed chairman David Turner and the rest of the board members have thought it would be more appropriate to choose a younger successor that can lead the bank for a decade or so.

Industry reports said that Narev's appointment also by-passed Ross McEwan, who had led CBA's retail banking segment all these years.

Sydney Morning Herald said that "CBA now faces the real prospect of losing Mr McEwan, a technology specialist, who behind Norris is the most experienced banker inside CBA. One or two other top level executive departures are also expected to follow over time."

The 44 year-old Mr Narev, formerly from McKinsey & Co consultant, was initially brought into the bank as head of strategy and later on assigned to lead CBA's small business bank.

Analysts said that although Mr Narev may have taken an important share of the market from rivals, small business is not CBA's niche which is still in retail and institutional banking.

In CBA's emailed statement, chairman Mr Turner said that Mr Narev successfully transformed CBA's business and private banking division and was able to make efficiency gains for the company.