What is AIM, the Alternative Investment Market?
AIM is the London Stock Exchange's market for smaller and growth-stage companies, operating under lighter rules than the Main Market with Nomad-supervised governance.
AIM (the Alternative Investment Market) is the London Stock Exchange's dedicated market for smaller, younger, and growth-oriented companies. Launched in June 1995 as a replacement for the Unlisted Securities Market, it was designed to give businesses access to public capital without the full regulatory burden of a Main Market listing.
The defining characteristic of AIM is its use of nominated advisers, or Nomads. Every AIM company must retain a Nomad at all times. The Nomad — typically an investment bank or specialist firm approved by the LSE — is responsible for advising the company on its obligations under the AIM Rules and for confirming to the exchange that the company is appropriate for admission and ongoing membership. This model shifts much of the supervisory burden from the regulator (the FCA) to the Nomad, allowing the market to operate with greater speed and flexibility.
AIM companies are not required to have a minimum trading history, minimum market capitalisation, or to place a set percentage of shares with the public before admission. This makes AIM accessible to early-stage businesses in sectors such as mining, biotechnology, technology, and natural resources that might struggle to meet Main Market requirements. The trade-off is lower liquidity: many AIM stocks are thinly traded, bid-offer spreads can be wide, and price movements are often more volatile than on the Main Market.
For UK private investors, a notable feature of many AIM shares is Business Property Relief (BPR): qualifying AIM shares held for at least two years can be passed on free of Inheritance Tax, making AIM a popular component of estate planning for UK taxpayers. The tax advantages are real, but investors should weigh them against the higher risk profile of smaller-company shares.