Speaking after BNZ reported a 3.4 per cent rise in half-year cash earnings for its banking operations to $400 million yesterday, Thorburn admitted he was feeling some "fear" about his new position at the helm of the much bigger Aussie bank.
"It's said that leaders should always be between fear and excitement," he said. "There is a little bit of fear - it's a big job and it's demanding and there are lots of expectations. But the opportunity to lead a big company and to make a difference to people in the company and our customers is huge."
Thorburn will replace Cameron Clyne, the current chief executive of National Australia Bank, on August 1. Clyne was previously chief executive of BNZ up until 2008 when Thorburn took over.
Thorburn said he was proud of the strengthened balance sheet the bank had built since the global financial crisis.
"I've got lots of great memories of our people and their skills and capabilities."
Thorburn described BNZ's half-year result as "solid" and said it reflected growth in underlying profit, tight management of expenses and a reduction in bad debts on the back of an improving economy.
BNZ's customers, particularly its business clients, had become "less stressed" as the economy improved, which helped reduce bad debts, he said.
The bank reported impairment losses of $38 million, down from $73 million in the half-year period a year earlier.
"Our balance sheet and funding position is really strong," Thorburn said. "We feel pleased with [the result] overall."
The bank said customer deposits increased by $4.6 billion, or 12.4 per cent.
BNZ said its core funding ratio - which requires banks to source most of their funding from retail deposit and longer-term wholesale sources - was above 85 per cent on March 31, exceeding the Reserve Bank's minimum requirement of 75 per cent.
Net interest income was $802 million, up from $778 million in the half-year a year earlier.
Thorburn said the Reserve Bank's introduction of high loan-to-value (LVR) restrictions on home loans had a "significant impact" on BNZ during the half but that had "settled down".
LVRs aim to cool a surging property market in parts of the country, particularly Auckland.
"We're actually starting to do some above 80 per cent [LVR] lending," Thorburn said.
BNZ said its average lending volumes grew by 5.2 per cent to $62.5 billion during the half-year. The increase was driven by a "strong business lending portfolio experiencing steady growth in institutional banking and agribusiness", the bank said.