A spokesman for Australia's fourth-largest lender said its CEO Andrew Thorburn would take a holiday after its annual shareholder meeting on Wednesday, where investors are likely to cast a protest vote against the pay packages of its top executives.

Thorburn would "return to work for the release of the Royal Commission's final report, and to consider and lead NAB's response," a spokesman said in an email.

"He will then take a month's long service leave to refresh, recharge and spend time with his family before returning to lead NAB through the next stage of our transformation."

Billions of dollars have been wiped off the value of NAB and its three larger rivals this year as the Royal Commission inquiry into the financial sector exposed a greed-driven culture in which staff were incentivized to mislead customers.

The inquiry is due to release its final report by Feb. 1, 2019. Analysts expect the report will recommend substantial structural and regulatory changes in the banking, financial advice and fund management sectors. The lawyers running the inquiry have said they may recommend referring some cases to criminal prosecutors.

The CEOs of NAB's three larger rivals - Commonwealth Bank of Australia, Westpac Banking Corp and Australia and New Zealand Banking Group Ltd - will take about three weeks off from next week and return to work in mid-January, as is common practice in Australia. NAB Chief Financial Officer Gary Lennon will act as CEO in Thorburn's absence.

Thorburn's holiday is scheduled to start after NAB's annual shareholders' meeting where investors are expected to vote down the bank's executive pay plans, reflecting widespread anger against the sector as a result of the inquiry. "It's hard to think that investors could be more disappointed than they already are, but this probably won't be helpful," Dennis Shore, a representative of the Australian Shareholders' Association, referring to Thorburn's long holiday.

"There's a lot of work to be done so this does seems unusual, but on the other hand you can see the need for the leader of the bank to be in good shape to tackle the task ahead over the next year or two."

(Reporting by Paulina Duran; Editing by Muralikumar Anantharaman)

By Paulina Duran