The £1.7bn merger between Virgin Money and CYBG has gone ahead this morning (15 October).
Earlier this year the two challenger banks agreed to a takeover deal which they claimed would create "the first true national competitor to the large incumbent banks."
As part of today's announcement Virgin Money's chief executive, Jayne-Anne Gadhia, has stood down alongside the company's chairman, Irene Dorner.
Jim Pettigrew, chairman of CYBG, said: "I am delighted we have completed the acquisition of the Virgin Money business.
"It is clear to us that the combined group can transform the UK banking landscape and offer real benefits to customers and communities throughout the UK.
"Since our IPO in 2016, the CYBG board and leadership team has established CYBG as a strong and sustainable business, with a track record of delivery and the credentials to deliver a transformational combination with Virgin Money.
"This transaction can deliver real value for all shareholders and create a powerful force in UK banking."
As part of the deal 540 million new CYBG shares have been listed on the London Stock Exchange while Virgin Money's listing has been cancelled.
The group's operations will come under the Virgin brand in a licensing deal with Sir Richard Branson's Virgin Enterprises.