Nelson, 76, replaces Mark Tucker who helped steer the Asia-focused bank for eight years.

The London-headquartered bank already switched chief executives in September 2024, with Georges Elhedery replacing Noel Quinn who had been in charge for around five years.

"I look forward to continuing to work with the board, Georges and the wider management team as we deliver on our strategic and financial objectives," Nelson said in a statement confirming his appointment.

Under Quinn and Tucker, the bank carried out major restructuring, including hefty job losses, and oversaw the bank's pivot towards Asia, where it generates most of its revenue.

Nelson, who in a previous senior role at KPMG advised and audited international banks, had been interim chair of HSBC since October.

He also served on the board of British energy group BP.

Following news of Nelson's appointment, shares in HSBC fell 1.1 percent in early deals on London's benchmark FTSE 100 index, which was flat overall.

Nelson's "prior reluctance to commit to a full term raises questions about the permanence of this appointment", noted Matt Britzman, senior equity analyst at Hargreaves Lansdown.

"The seat is filled, at least for now, so this shouldn't have a major impact on shares.

"But it will reinforce investor concerns around leadership stability, and longer-term succession planning, at a critical juncture for the bank."

HSBC's latest earnings showed profits fell in the third quarter, with the bank's bottom line weighed down by legal provisions related to the late Bernard Madoff's huge investment fraud.

The bank added in its late October update that commercial real estate conditions remain challenging in China, with government stimulus measures yet to trigger a material improvement in buyer sentiment.

HSBC recently proposed a $14-billion buyout to privatise Hang Seng Bank in the finance hub.

HSBC was founded in Hong Kong and Shanghai in 1865 -- but has been based in Britain since 1993.