Hargreaves Lansdown is planning to create a further 35 marketing jobs over the next 18 months.
The firm currently employs 71 people in its marketing department in Bristol but said the team would be expanded to take advantage of opportunities in the market.
Hargreaves said this was an important step to improve its relationship with the group's 876,000 clients, of whom 55,000 have interacted solely by mobile device over the last three months.
Chris Worle, digital director at Hargreaves Lansdown, said: "Against the backdrop of the UK's huge savings and investing gap, and an ongoing trend towards people using digital channels such as mobile, we see significant opportunities ahead in the investment, pensions and savings markets.
"Marketing has always been an important part of our business and has helped to set us apart. We want to deepen our relationship with our clients, and improve the service and experience we offer.
"Alongside this we are looking at new ways to grow our markets and help more people to invest for their future."