Although the two brothers continue to have significant shared business interests – including EG Group, Castore and HVS Systems – Zuber is not listed as a shareholder in Boulder.
Both men are worth a combined £5bn and rose from humble beginnings in Blackburn to build the UK’s largest petrol station empire, EG Group.
In 2020, they bought the UK’s third-largest supermarket Asda, which has 150,000 employees and 1,000 stores.
There has been speculation of a rift between the brothers as their business interests have diverged, although this has been denied by Mr Issa.
The 53-year-old confirmed he was in a relationship with Ms Price, 41, earlier this year following a report in The Telegraph.
Ms Price had previously been an accountant at EY, which served as Asda’s auditor up until July last year.
After leaving EY she joined Alvarez and Marsal in February to lead the firm’s private capital division.
When asked about the new Boulder investments, Ms Price said: “These investments are aligned to my passion for working with entrepreneurial businesses in the UK.”
Boulder is listed on the Jersey Financial Services Commission register, with Mr Issa and Ms Price described as joint shareholders.
GoThrift runs an online fashion store where shoppers can buy vintage clothing. It was originally founded by three friends in 2019 to sell clothes on eBay before expanding.
Carl Walker, who co-founded GoThrift, said he was “thrilled” to have the couple on board.
“It’s fantastic to have two investors who not only believe in our vision and our commitment to sustainable fashion but are also dedicated to supporting both the business and our team on our entrepreneurial journey,” he said.