AIM, London's growth market

What AIM is, and how it differs from the Main Market

AIM, short for Alternative Investment Market, opened on 19 June 1995. The London Stock Exchange runs and regulates it itself. In law AIM is a multilateral trading facility and an SME growth market, not a regulated market. That is the real dividing line from the Main Market, where the FCA decides on admission to the Official List and a sponsor walks you through it. On AIM the exchange decides, and the sponsor's place is taken by the Nominated Adviser, the Nomad.

AIM describes itself as a market where investors carry the risk, and the exchange does not review the admission document on its merits. That puts all the more weight on the company and its advisers. Under the rules an AIM company is normally expected to be set up much like a UK plc. For a founder elsewhere in Europe that usually means a British PLC as the holding company above the operating business. How you get there is set out under PLC formation.

The new AIM Rules since 5 August 2026

The London Stock Exchange calls the reform the biggest change to the AIM Rules in two decades. The rulebook has been in force since 5 August 2026. The headline points, in the exchange's own summary:

An easier way in: information that is already public need not be repeated in the admission document, needless third-party reports fall away, and a company reporting under UK GAAP no longer has to switch accounting standards. More room on acquisitions: a planned reverse takeover no longer means an automatic suspension of trading. A fast track for international companies already quoted on other markets. And a new job description for the Nomad, moving from policing the rules towards ongoing advice.

On one point nothing has changed for you: the company still has to be in order when it is admitted. The reform saves paperwork, not care.

The Nominated Adviser: required every single day

To come to AIM you must appoint a Nominated Adviser, and an AIM company must have one at all times. The Nomad assesses whether your company is appropriate for AIM, takes it through admission and then advises it on the AIM Rules on an ongoing basis. Its duties are owed to the London Stock Exchange alone, not to you.

If an AIM company loses its Nomad, the exchange suspends trading. If no new Nomad is appointed within 6 weeks, the admission is cancelled. Lawyers, reporting accountants and a broker complete the team, as the exchange itself lists them. We are the part that runs the company: registers, minutes, resolutions, deadlines. That leaves the Nomad free to do its own job instead of chasing missing papers.

What goes in the calendar after admission

Listing is the start of the administrative work, not the end of it. An AIM company publishes its audited annual accounts no later than 6 months after its financial year end. Half-year reports are due no later than 3 months after the end of the half year. AIM shares must be freely transferable and eligible for electronic settlement, which means work for any company still holding old paper certificates (more under dematerialisation).

On corporate governance AIM stays deliberately flexible. The company names a recognised code it follows, but it is not bound to apply it on a comply-or-explain basis; it explains how its board and processes are set up. Where a business has not earned independent revenue for two full years, a lock-in applies as well: related parties and certain employees do not sell shares for the first 12 months after admission.

We take on these running obligations under PLC Company Secretary: board calendar, general meetings, registers, Companies House filings and liaison with the Nomad.

Sources: London Stock Exchange: AIM Rules for Companies (August 2026, PDF); London Stock Exchange: AIM rule changes snapshot (PDF); London Stock Exchange: AIM; FCA: PS25/9 (PDF)