The takeover will create a combined multi-manager business with £6.6bn in assets.
As part of the deal, the UK multi-manager fund management team at Architas, headed by Sheldon Macdonald, will merge with Liontrust's Multi-Asset investment team headed by John Husselbee.
Sheldon Macdonald will become deputy head of multi-asset at Liontrust.
The Architas UK Fund Management Team, as part of the Liontrust Multi-Asset investment team, will continue to manage 25 risk profiled and non-risk profiled funds.
The Liontrust brand will be used for all the UK Architas funds but Liontrust says there will be no change to the risk/reward objectives of the funds.
As a result of the deal Liontrust's assets under management and advice will rise by £5.6 billion to £25 billion.
John Ions, chief executive of Liontrust, said: "The Architas UK Investment Business is an important strategic acquisition for us to meet the growing demand for investment solutions from advisers and their clients over the next few years. It builds on and complements our existing investment solutions of multi-asset portfolios, sustainable managed and equity income funds.
"Buying the Architas UK Investment Business will expand our distribution among financial advisers through the scale of the combined businesses, the strength of the merged investment team, the broad range of multi-asset multi-manager portfolios and funds and enhanced client service.”
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