The deal means Standard Life Aberdeen plc is one of the largest active fund management firms in Europe and one of the world’s largest investment companies, running £670bn with clients in 80 countries.

When the planned merger was announced in March this year the firms said they expected annual cost savings of around £200m within three years of the merger being completed.

The group’s investment business, Aberdeen Standard Investments, manages £583bn of assets, offering clients access to a range of developed and emerging market equities and fixed income, multi-asset, real estate and alternatives solutions.

On the pension and savings side, Standard Life has around 4.5 million customers with one in six people auto-enrolled into a workplace pension coming under its scope. Standard Life Aberdeen will have offices in 50 cities around the world. It has a market cap of over £11bn.

Martin Gilbert, chief executive of Standard Life Aberdeen, said: “Our priority remains the delivery of strong investment performance and the highest level of client service. The merger deepens and broadens our investment capabilities, and gives us a stronger and more diverse range of investment management skills as well as significant scale across asset classes and geographies. We believe this will enable us to deliver an even better proposition and service to our enlarged client base.”

Jason Hollands, managing director at Tilney Investment Management, said the transaction has been concluded but the integration journey has only just begun, so at this stage there is no need for investors to do anything.

He said: “From our perspective we want to first see how things shape up in combining any teams and above all evidence that really key fund managers are retained through this process. The skills overall between the two businesses are very complementary, with Standard Life having major franchises in areas such as absolute return and developed market equities while Aberdeen has a big presence in emerging markets and Asian equities. Areas of overlap include property (where co-heads have already been confirmed), multi-manager and socially responsible investing.

“The investment trusts managed by the previous two businesses are essentially ring-fenced as they have their own independent Boards and therefore any proposals to change managers on these, would need to be approved by the trusts. However, there is no direct overlap in the two investment trust ranges, so I wouldn’t expect to see any changes.”

He added that for now, it is a case of “wait and see what all this means” but said overall, he’s “very relaxed about the deal”.