An investment fund of variable size in corporate form. Broadly, it is a collective investment scheme that acquires investments such as stocks and shares, gilts, bonds and cash with the aim of spreading investment risk and giving its investors (who hold shares in the OEIC) the benefit of the results of the management of those investments. OEICS are defined in section 236 of the Financial Services and Markets Act 2000.

The glossary to the FCA Handbook sets out the full definition of this term. When considering this term in the context of financial services reference should be made to the FCA Handbook glossary definition of open-ended investment company.