Both investment houses are owned by the New York-listed financial services firm Ameriprise Financial. Now operating under one brand, they manage combined assets of £324 billion ($506 billion) across developed and emerging market equities, fixed income, multi-asset solutions and alternatives.

"We have brought together two well established, successful asset managers under one global brand, offering clients a broader set of capabilities and a truly global presence,” said Columbia Threadneedle Investments' chief executive, Campbell Fleming.

“For Threadneedle, it builds on our established businesses in EMEA and Asia-Pacific. Under the banner of Columbia Threadneedle Investments, we now also have a brand presence in North America, the largest investment market in the world,” Fleming said.

, which presents itself with a new logo, said there would be no change to established investment teams, strategies and processes, nor to the group's corporate structure.

Ameriprise as a whole holds $806 billion in assets under management and administration.