ANZ Bank's New Zealand chief executive David Hisco is taking extended sick leave and Antonia Watson, who heads retail and business banking, will take over as acting chief executive, the bank says.
In a note to ANZ's staff, Watson says Hisco's doctor says his prognosis is good so long as he slows down and takes time off to recover.
"David has told me he's keen to get back to work as soon as possible but realises how important his health is. We obviously all wish David a speedy recovery," she says.
As a result, the chief executive of ANZ's Australian parent, Shayne Elliott, asked Watson "to fill in for David on group executive meetings and have responsibilities for our business in the Pacific," she says.
"We have a great team and the second half of the financial year is going well so I'm sure we'll all keep the ship running smoothly until David returns."
ANZ has suffered a couple of regulatory blows this month with the Reserve Bank forcing it to hold more capital against housing and farm lending from June 30 and to use the standardised model for calculating its operational risk capital rather than its own internal model.
That's because it had been using its internal model for calculating ORC since December 2014 without first getting RBNZ approval.
The ORC measure was one of about 45 internal models ANZ uses and it can continue to use the other 44.
Only the four major banks, which are all owned by Australia's major four banks, are allowed to use their own internal models to calculate capital.
In February, RBNZ revealed that ANZ needed only slightly more than half the capital that the government-owned Kiwibank needs to back each $100 of mortgage lending because of the advantage it gains from using internal models.
Kiwibank, along with all the New Zealand-owned banks, is required to use standardised models.
Also earlier this month, ANZ reported net profit for the six months ended March fell to $929 million from $964 million in the same six months a year earlier.