Spotlight series
Overview
AIM turned 30 last year, a significant milestone that marks the death of its ‘youth’ and maturity into an established market looking forward to a long and successful future.
AIM was created to provide market access to capital for smaller, growing businesses that otherwise couldn’t access AIM’s bigger brother, the Main Market – one of the most renowned capital markets in the world, boasting the FTSE 100, an estimated market capitalisation of £4.4 trillion and a total list of issuers over 1,000 strong. However, AIM has stepped out of the shadow of its sibling and forged its own path as the self-proclaimed home of “innovative companies”. Since its birth, AIM has supported more than 4,000 companies to raise nearly £135 billion (£48 billion on IPO and £87 billion in further fundraising). It is the most active growth market in Europe, and over the last 5 years, 45% of all capital raised on European growth markets has been on AIM.
Key differences between AIM and the Main Market
Feature |
AIM |
Main Market |
|---|---|---|
Market Type |
A sub-market of the LSE originally designed for growth companies |
Primary market for larger, well-established companies |
Advisor |
Nomad at all times |
Sponsor required on listing |
Regulatory Oversight |
Regulated by the exchange itself; Governed by the AIM Rules for Companies; oversight by the Nomad |
|
Approval Requirement |
No FCA approval required of the Admission Document unless qualifying as a public offer Prospectus |
Prospectus must be reviewed and approved by the FCA |
Disclosure Level |
Moderate; tailored disclosures based on AIM rules |
High; standardised disclosures governed by the Disclosure and Transparency Rules |
Investor Protection |
Lighter statutory protections; relies on Nomad and exchange rules |
Full statutory protections under FSMA and Prospectus Regulation Rules |
Minimum Market Cap |
No formal minimum |
£30 million minimum expected market capitalisation |
Free Float Requirement |
No formal requirement |
Minimum 10% of shares in public hands (ESCC category requires 10%) |
Significant transactions |
Class tests as per AIM rules |
Disclosure needed for significant transactions ≥25% in class tests |
Corporate Governance |
Choice available but typically QCA Code |
Comply or explain against the UK Corporate Governance Code |
Tax Reliefs |
AIM shares may benefit from EIS, IHT relief and stamp duty exemptions |
Main Market shares do not typically benefit from these tax reliefs |
In recent years, we have seen an increase in companies migrating markets, particularly making the voyage from AIM to the Main Market, although some are transferring from the Main Market to AIM. According to AJ Bell, since 2004, over 130 companies have moved from AIM to the Main Market. According to LSE data to the end of December 2025, seven companies have made the move from AIM to the Main Market last year. So far in 2026, CVS Group Plc and GlobalData Plc have made the same move. Famous former alumni graduating from AIM to the Main Market include Domino’s Pizza, Asos (fashion and clothing), Unite (student housing), and Entain (gambling).
Why move from AIM to Main Market?
Signalling and public profile
Companies that have come to AIM, adapted to the demands of being a publicly listed company, grown and thrived, and are now ready for the next stage in their development, often seek to make the jump to the Main Market, attracted by the promise of enhanced reputation and prestige. A listing on London’s premier market signals maturity and financial stability. The perception and cachet around the Main Market, whether earned or not, can lead to increased investor confidence and a larger public profile. This enhanced public profile also extends to all the company’s stakeholders. From AIM’s perspective, the move is not viewed with any hostility but is instead celebrated as another name on the long rap sheet of AIM success stories.
Liquidity and access to capital
The following of Main Market companies tends to be larger; from traditional media outlets and publications to financial analysts and investors. With greater coverage comes access to more and deeper pockets. The pools of capital and liquidity available to companies on the Main Market often far exceeds those available on AIM.
Certain investors (typically institutional investors and pension funds) will not invest in AIM stocks. Other investors cannot invest in AIM stocks (prevented by rigid investment policy). Several fall into the ‘will not, cannot’ category.
The Main Market also offers companies the opportunity to be included in various indices and tracker funds. Inclusion on the FTSE 100 or FTSE 250 indices is analogous to obtaining a blue tick on (pre-Musk) Twitter.
Regulatory reforms
Following years of sluggish performance, in July 2024, UK regulators enacted the most extensive overhaul to UK Listing Rules (UKLR) to boost the UK’s competitiveness as a global financial centre, and better compete against public markets in the US, the EU and further afield.
Many of these changes to the listing rules (which govern the Main Market) have narrowed the gap with the regulatory requirements of AIM (governed by the AIM rules). Furthermore, on 19 January 2026, the FCA implemented new prospectus rules which, amongst other things, increased the threshold for requiring a prospectus for secondary share issues from 20% to 75% of existing share capital. This significantly eases the regulatory and cost burden around secondaries, further narrowing the perceived gap in regulation between AIM and Main Market. AIM has historically been viewed as having less onerous regulation; it seems those days are numbered.
Is the grass greener?
The company must first assess whether the juice is worth the squeeze: balancing the promise of enhanced liquidity and prestige against the cost (both monetary and time) of the move. Whilst the Company should be able to table a Simplified Prospectus document if it has traded on AIM for more than 18 months, the costs are not negligible. A sponsor will be required to oversee the move along with financial, legal and other advisers to navigate the due diligence and regulatory compliance required. The company will have jumped through similar hoops on the production of their Admission Document for AIM and may be loath to negotiate the bureaucracy once again.
On the other side of the market move, the grass may not always be greener. Annual costs of being a public company on the Main Market can outweigh those on AIM and despite the narrowing of the rules, an increased regulatory burden of a Main Market listing remains. The increased press, investor and regulatory coverage can bring unwanted levels of scrutiny and pressure.
Companies also have to bear in mind the tax consequences for their shareholders. AIM stocks have historically qualified for 100% relief (reducing to 50% relief from 6 April 2026) for inheritance tax purposes, under business property relief, so long as the shareholder held the stock for at least two years. Moving to Main Market, this relief is lost so careful consideration must be given to the current and intended shareholder base (especially where IHT funds represent a material interest in the company).
Marketing to insert the linking paragraph at the end noting our team is experienced in AIM, Main Market listings as well as assisting in companies moving markets.
For more information on due diligence, please contact Joseph Baulf or Jack Devlin.
