Milestone, based in Australia, supplies financial software packages for fund managers and life and pensions companies.
Established in 1998, the company operates globally, with clients in Europe, North America, Asia, Australia and South Africa.
Milestone's clients include Citi, JP Morgan Chase and Zurich Financial Services.
The Milestone brief is the latest in a series of wins for Aspectus this year.
Others include Evoco Energy, business tech firms Exact and Ayima, and financial firms G2 Systems and Forefactor.