The rebrand is aimed at reinforcing the companiesâ strength across Europe, the US and the UK as well as expanding their footprint in Asia-Pacific, Latin America and the Middle East. Columbia Management is the 11th largest manager of long-term mutual funds in the US, with $358bn (Â£236bn) of assets under management (Aum).Together, Columbia and Threadneedle will have Â£316bn in Aum across emerging market equities, fixed income, multi-asset solutions and alternatives (including UK property).he rebrand is aimed at reinforcing the companiesâ strength across Europe, the US and the UK as well as expanding their footprint in Asia-Pacific, Latin America and the Middle East. Columbia Management is the 11th largest manager of long-term mutual funds in the US, with $358bn (Â£236bn) of assets under management (Aum).