A Sub-Threshold AIFM is a UK alternative investment fund manager whose total assets under management (AUM) do not exceed the Small AIFM thresholds set in the UK Alternative Investment Fund Managers Regulations, and therefore qualifies as a Small AIFM.
Small AIFM thresholds:
• €100 million, where alternative investment funds (AIFs) are leveraged; or
• €500 million, where all AIFs are unleveraged and investors have no redemption rights for at least five years.
Firms that do not meet these criteria are Above-threshold AIFMs and are therefore Full-Scope UK AIFMs; some Small AIFMs may also choose to opt into the Full-Scope regime.
Firms that meet the Small AIFM thresholds can operate either as Small Authorised or Small Registered UK AIFMs. Both are sub-threshold, but they sit in different parts of the UK regime: Small Authorised UK AIFMs hold a Part 4A permission to manage AIFs and are subject to the UK AIFM rules on a proportionate basis, while Small Registered UK AIFMs are registered under the small AIFM regime instead of being authorised and are supervised through a lighter registration and reporting framework.
As at Q4 2025, there are 1,284 UK AIFMs based on the total number of authorised and registered AIFMs regulated by the FCA. Full-Scope AIFMs make up the majority (685 firms, or 53.3%), followed by 466 Small Authorised AIFMs (36.3%) and 133 Small Registered AIFMs (10.4%).
