Clydesdale and Yorkshire Bank Group said its ordinary shares have today started unconditional trading on the main market of the London Stock Exchange.
The lender said its demerger from National Australia Bank has been fully implemented and it is now independent.
David Duffy, chief executive, said: “Today, CYBG has become a fully independent banking group for the first time since 1920 and it is a privilege for me to be leading the business at this pivotal moment in its 177-year history.
“We are the only UK banking group to have a dual listing in London and Australia and we have an enviably strong and supportive shareholder register which includes blue chip institutions and individual investors across Australia, the US and here in the UK.
“With the demerger and IPO successfully completed, I am confident that CYBG starts life as a listed company in great shape.
“Our large and loyal customer base and highly experienced team provide a strong platform from which to grow and we will present a very real challenge to our competitors here in the UK.
“Now everyone at CYBG - our board, the leadership team and every one of our employees - will focus sharply on creating an even better bank for our customers and our new shareholders.”
CYBG is registered in Leeds. Its head office is in Glasgow.
Jim Pettigrew, chairman, added: “Beginning life today as a newly independent listed company for the first time in almost a century and with a new shareholder base that truly does span the globe, we are uniquely positioned as the largest of all the UK challenger banks.
“With a clear customer-focused strategy being driven by one of the best management teams in banking, I am confident that CYBG has a strong and exciting future ahead.”