Third party mortgage administration firm HML, which employs 350 people in a call centre in Northern Ireland, has been sold to global business Computershare.
HML (Homeloan Management Ltd) has been off-loaded by Skipton Building Society in a £47.5m deal, which includes an adjustment for surplus working capital.
A spokeswoman for HML said there were "no plans for redundancies" as a result of the deal.
Skipton could receive more than the initial £47.5m depending on revenue growth in 2015 and 2016.
The Derry branch of HML is based in the city's Ulster Science and Technology Park on Buncrana Road.
There are also offices in Glasgow and Dublin, as well as at its base in Skipton.
HML's new parent company "has a strategic commitment to the UK and Europe's mortgage market", according to HML chief executive Andrew Jones.
He added that Computershare had bought HML in order to significantly invest in the mortgage servicer to allow it to take advantage of developing opportunities.
"I am delighted that HML and Computershare will be working together, and Computershare becoming our parent company is excellent news for the business and those who work at HML.
"Computershare is committed to investing in and growing HML, allowing us to continue to be the leading third-party mortgage administration company in the UK and Ireland," he said.
"With the desire to grow the business and develop the specialist expertise that HML has, it's clear to me that culturally we are much aligned with Computershare.
"HML has had 25 years of successfully delivering value to clients, customers, our people and our former parent, and this deal will secure the future of the company for many more years to come," he added.
Computershare Ltd is the UK subsidiary of the Australian parent company of the same name, which is listed on the Securities Exchange and employs 14,000 people around the world.
Mr Jones added that Computershare had a proven track record of mortgage servicing in the US and recently doubled its business to $35bn (£20bn) with the purchase of Specialized Loan Servicing (SLS) in 2011.
"Computershare has been looking for the right UK and Ireland servicer in which to invest and grow, and has chosen HML," he said.
In May this year, HML marked 10 years of operating in Derry. The company said the office had been central to HML expanding into the Republic, where it had made significant contract wins.
When it first opened in 2004, it had just 25 members of staff.
HML's main office will remain in Skipton.
HML currently has approximately £37bn of managed assets and 50 major clients, including banks and building societies.
In addition, HML provides 'standby' services to a further £60bn of assets.
In August 2013, investment rating service Standard &Poor revised the outlook of HML's primary servicing of residential mortgages in the UK from stable to positive.
It also affirmed the above average rankings for HML as a primary and special servicer of UK residential mortgages, and as a primary servicer of residential mortgages in Ireland.
In the same month global rating agency Fitch announced that HML's UK residential primary servicer ratings had been upgraded to RPS1- from RPS2+.