AIM reforms: what the LSE's changes mean for London's growth market

Proposed amendments to the AIM Rules for Companies and AIM Rules for Nominated Advisers (Nomads) give formal effect to the widely supported proposals set out in the London Stock Exchange's November 2025 feedback statement on shaping the future of AIM. 

Market participants have only until 2 July to respond to the proposed amendments as the LSE presses ahead with the most extensive overhaul of AIM's rulebook in years. The tight response deadline is a strong indication of the LSE's intentions to bring the changes into effect promptly. 

The overarching purpose of the LSE's reforms is to reassert AIM's pre-eminence and evolve its rules around what companies, founders and investors need. The changes are designed to differentiate AIM from the Main Market; reduce unnecessary regulatory burdens on admission and support AIM companies undertaking transactions and fundraisings. Explicit provisions will also be added to the introduction to the AIM Rules which set out the nature of AIM's buyer-beware model, recognising that investors need to consider the risk profile of specific investments and take responsibility for their investment decisions. 

Reducing the burden on admission 

The LSE is working to redesign the AIM admission document with a view to modernising, simplifying and streamlining the admission process and will consult on the content in due course. 

In the meantime, the LSE has confirmed its intention to remove the requirement for directors to make a working capital statement in the AIM admission document. Instead, the LSE proposes clear disclosure of the capital resources available to the applicant, its financial obligations, and proposed fundraising needs over the following 12-months. 

The LSE also intends to embed into the rules the existing policy under which UK-incorporated AIM companies may use UK Generally Accepted Accounting Principles (GAAP), specifically Financial Reporting Standards 102 instead of International Financial Reporting Standards (IFRS) for historical financial information in their admission documents. 

Other local GAAPs may also be permitted where IFRS equivalency is demonstrated. The ability to use UK GAAP addresses feedback about the cost of IFRS conversion and complexity relative to the limited value provided to investors. It would also allow AIM companies to adopt the most appropriate standards for their sector, particularly where peers also report in local GAAP. 

Other confirmed changes to reduce the burden on admission include allowing an AIM company to incorporate information into the admission document by reference, permitting a sell-down in the first 12 months post-admission for certain connected party transfers and no longer requiring an AIM admission document for a second line of securities. 

Enabling fundraising 

One of the most notable new proposals is the introduction of a "Capital Access Window". The LSE is proposing rule changes that will enable an AIM company undertaking an equity fundraise to voluntarily request a temporary suspension, the Capital Access Window, in order to manage the fundraising process more closely and approach a broader investor base, including retail investors, during the suspension period. The LSE does not propose to specify the duration of the Capital Access Window, giving flexibility to AIM companies, noting that it will be in the interests of the AIM company and investors to restore the securities to trading as soon as possible. 

Acquisition activity 

The LSE is proposing a number of changes to support acquisition strategies for AIM companies. 

The class tests are being simplified and the LSE is proposing to align AIM with the Main Market to increase the class test threshold for determining whether a transaction constitutes a substantial transaction from 10% to 25%. 

An acquisition will no longer automatically be considered a reverse takeover solely because it exceeds 100% in the class tests where there is no fundamental change to the AIM company's business, board or voting control. Instead, such acquisitions will be classified as substantial transactions under AIM Rule 12, with disclosure calibrated to what investors need in order to understand the acquisition and its impact. 

Where a transaction is a reverse takeover, the consultation proposes that there will be no automatic suspension on notification where the Nomad is satisfied that appropriate alternative disclosure can be made to enable investors to make an informed assessment of the proposed enlarged group. A supplementary AIM admission document will not be required where there is a delay between shareholder approval of a proposed reverse takeover and completion, provided there is no significant new factor, material mistake or material inaccuracy. Entering into an option agreement will not constitute a reverse takeover in contemplation on notification if certain conditions are met. 

Founder-led companies 

The consultation proposes to implement into the rules the current policy approach that special voting shares are acceptable at admission to AIM, enabling founders to retain control. This should be attractive to many founder-led companies considering admission to AIM and is consistent with a "buyer-beware" market in which investors can make their own risk assessments. 

The LSE also acknowledges that AIM companies may need flexibility to structure director remuneration in ways that attracts talent and retains the skill and experience required to deliver their strategy. Accordingly the consultation proposes that Nomads will not be required to provide a fair and reasonable opinion on non-standard director remuneration where they are satisfied that contractual terms provide reasonable commercial protections for the AIM company, such as good/bad leaver provisions. Where there is any uncertainty as to whether reasonable commercial protections have been provided, the matter should be resolved by a shareholder vote.

Corporate governance 

Market feedback indicated that the current "comply or explain" regime against a recognised code has resulted in many companies feeling compelled to comply with standardised governance provisions rather than explain their approach. Accordingly, the consultation proposes that an AIM company is not required to adopt, or comply or explain against, a particular corporate governance code. Instead, a recognised code may be used as a framework for considering its governance approach. 

To support investor understanding of each AIM company's corporate governance approach, the consultation proposes five key areas for disclosure that investors have consistently prioritised: board composition; directors' roles and responsibilities; remuneration and performance; risk and controls framework; and approach to investor relations. 

The consultation also proposes changes to allow AIM companies the opportunity (but not the obligation) to voluntarily disclose details of proxy advisor engagement and additions to the AIM Rules designed to support AIM companies which are the subject of abusive commentary or speculation. 

International growth 

AIM is an international growth market and accordingly, the LSE proposes to replace the current AIM "Designated Market" route with a new "Express Market" route, designed to enable companies from a wider range of international jurisdictions to join AIM through a tailored, proportionate and accelerated admission route based on International Organisation of Securities Commissions principles. This aligned with the standard used for international companies for Main Market listing rules. Notably time frames will be shortened and lock-ins will not apply. There will also be an accelerated admission process to the Express Market for certain Main Market companies. 

The consultation also proposes a new "Dual Market Applicant" route for companies seeking simultaneous admission to an Express Market and AIM, enabling them to leverage the same disclosures for both markets and rely on the document prepared for admission to the Express Market for AIM admission purposes. Dual market applicants would be required to raise at least £6 million, or equivalent, as part of an initial public offer. 

Nomad reforms 

Given that a significant number of respondents considered AIM Rule 11, which requires disclosure of price-sensitive information without delay, to be duplicative of the requirement under the UK Market Abuse Regulation (MAR), the LSE proposes to remove this disclosure obligation. In its place, a new AIM Rule 11 is proposed which will focus on the value of the Nomad's public market experience to support an AIM company in understanding the potential market impact of developments in its business, ensuring the company has full information when considering its own UK MAR obligations. 

A new nominated adviser technical note setting out the LSE's expectations in respect of certain of the Nomad's responsibilities is being consulted on separately. 

Osborne Clarke comment 

This short consultation represents the formal crystallisation of the reform agenda that has been building since the LSE's April 2025 discussion paper. Many of the changes have already been applied in practice through derogations granted since November 2025. The commitment to reduce unnecessary friction on admission, in mergers and acquisitions execution and in ongoing obligations is designed to reset the buyer-beware ethos that has underpinned AIM's success for 30 years. 

For companies currently on AIM or contemplating admission, the proposals reduce cost, simplify documentation and provide greater flexibility, particularly for founder-led businesses and companies with international listings. 

For Nomads, the shift in emphasis from compliance oversight towards corporate finance advisory will require a recalibration of working practices and engagement with the new technical note consultation.