Each of the Investment Association sectors has a clear definition setting out the criteria that funds must fulfil. Most sectors are organised around the principal asset types in which the fund should invest.
For example, the UK All Companies sector comprises funds that invest at least 80% of their assets in UK equities, which have a primary objective of achieving capital growth. Within any Investment Association sector, the funds may offer a considerable variety of specific asset mixes, strategies and risk profiles.
Here you can look up individual sector definitions.