Mr Vikram Pandit, who ran Citigroup during the financial crisis, said developments in technology could see some 30 per cent of banking jobs disappear in the next five years.
Artificial intelligence and robotics reduce the need for staff in roles such as back-office functions, Mr Pandit, 60, said yesterday in an interview with Bloomberg Television. He is now chief executive officer of Orogen Group, an investment firm that he co-founded last year.
"Everything that happens with artificial intelligence, robotics and natural language - all of that is going to make processes easier," said Mr Pandit, who was Citigroup's chief executive officer from 2007 to 2012. "It's going to change the back office."
Wall Street's biggest firms are using technologies including machine learning and cloud computing to automate their operations, forcing many employees to adapt or find new positions.
Bank of America's chief operating officer Tom Montag said in June that the firm will keep cutting costs by finding more ways in which technology can replace people.
While Mr Pandit's forecast for job losses is in step with one made by Citigroup last year, his timeline is more aggressive. In a report in March last year, the lender estimated a 30 per cent reduction between 2015 and 2025, mainly due to automation in retail banking. That would see full-time jobs drop by 770,000 in the United States and by about one million in Europe, Citigroup said.
JPMorgan Chase CEO Jamie Dimon cautioned in June against overreacting to the impact of technology on jobs. While the bank is using technology to cut costs, that helps create other opportunities, he said in an interview published on LinkedIn. He predicted that employee numbers at his firm will continue to rise - as it hires more technology workers.
The banking industry is becoming "enormously competitive", Mr Pandit said, adding that he foresees the emergence of "specialist providers" as well as consolidation in the industry. "I see a banking world going from large financial institutions to one that's a little bit more decentralised," he said.
Since leaving the firm, Mr Pandit has invested in non-bank financial start-ups such as student-loan venture CommonBond and home equity finance firm Point Digital Finance. He formed New York-based Orogen last year with investment firm Atairos Group to acquire stakes in mature financial services companies.