London Stock Exchange overhauls AIM Rules: effective from 5 August 2026

On 5 August 2026, the London Stock Exchange (LSE) published revised AIM Rules for Companies (the AIM Rules) and AIM Rules for Nominated Advisers, which came into effect immediately. The finalised rules follow a consultation earlier this year on a package of significant reforms designed to reposition AIM between the LSE's Main Market and Private Securities Market, reduce unnecessary burdens on AIM companies and attract a diverse range of companies. 

Key changes to the AIM Rules include admission changes, changes to support M&A activity, a capital access window, changes to support founder-led companies and the removal of the comply or explain corporate governance code requirement, as well as a new express market route.

Admission changes

Working capital statement removed

The requirement for a working capital statement in an AIM admission document has been removed and replaced with new disclosure requirements regarding the applicant's material capital resources, material financial obligations, the use of proceeds from any fundraising on admission and the directors' reasonable opinion of the applicant's future fundraising needs for the next 12 months. 

Incorporation by reference 

To reduce the cost and length of an admission document, incorporation by reference to information that is publicly available is now permitted. As the purpose of the rule change is to provide flexibility, the LSE has not prescribed an exhaustive list of information that may be incorporated by reference; rather, a reasonable assessment can be made by an AIM company with the support of its nominated adviser. 

UK GAAP option

UK incorporated companies may use UK GAAP instead of IFRS for the purposes of their financial reporting. An applicant's nominated adviser can approach AIM Regulation on a case-by-case basis in respect of other local accounting standards.

Changes to support M&A activity

Reverse takeover redefinition 

An acquisition will only be considered a reverse takeover if it is substantively transformative. Accordingly, an acquisition which exceeds 100% in the class tests but does not result in a fundamental change to the AIM company's business, board or voting control will instead be classified as a substantial transaction.

The LSE has not proposed a mandatory shareholder approval requirement solely by reference to a transaction exceeding 100% in any of the class tests. Rather, it has adopted a more proportionate approach: the AIM company, via its nominated adviser, should consult the LSE in relation to a substantial transaction which is not a fundamental change of business, where the class tests exceed 100%, and where the company is not proposing to seek shareholder approval.

Furthermore, an AIM company will not be required to suspend trading in its securities on notification of a reverse takeover in contemplation where the nominated adviser is satisfied that appropriate alternative disclosure can be made to investors and the LSE is consulted in advance of the notification.

Substantial transaction threshold raised to 25% 

The threshold for whether a transaction constitutes a substantial transaction has been raised to 25%, in line with the UK Listing Rules.

Capital access window

An AIM company seeking to undertake a fundraise or corporate transaction involving the issue of AIM securities may voluntarily request that its securities be temporarily suspended to assist in managing the fundraising process while conducting negotiations. 

The intention behind this change is to make it easier for AIM companies to access a broader range of investors. As is the case when an AIM company's shares are suspended from trading in all other scenarios, its obligations under the UK Market Abuse Regulation (UK MAR) and the AIM Rules continue to apply during a capital access window. 

Changes to support founder-led companies

Special voting shares

Special voting shares will be permitted on admission to AIM to enable founders to retain control. They may only be issued if the applicant includes in its constitutional documents specific provisions set out in the AIM Rules in relation to who the shares may be issued and transferred to, and carves out certain matters in relation to which the holders of such shares cannot exercise voting rights. Special voting shares cannot be issued, nor can rights be extended following admission.

The LSE has not mandated a fixed time limit or sunset period, considering that investors will naturally make their own determination on the terms of the special shares when reaching their investment decision. This approach is intended to ensure the flexibility required by founder-led and growth companies, while also ensuring that investors can make informed decisions through disclosure of the share structure on admission. 

Remuneration opinion changes

Nominated advisers are no longer required to give a fair and reasonable opinion on non-standard director remuneration where they are satisfied that contractual terms provide reasonable commercial protections for the company. 

The guidance regarding non-standard remuneration remains subject to the normal parameters and requirements of AIM Rule 13, including: the 5% class test threshold; consideration by the AIM company of the terms of remuneration in accordance with its corporate governance arrangements; and a fair and reasonable statement from independent directors of the AIM company in the transaction notification. 

Additionally, the LSE has made a change to delete references to persons discharging managerial responsibilities (PDMRs) within the definition of related party, recognising that this potentially leads to a very wide definition of "related party" and a wider definition than under the UK Listing Rules. 

Comply or explain corporate governance code requirement removed

AIM companies no longer need to adopt a recognised corporate governance code or comply or explain against one. Instead, AIM Rule 26 specifies five key areas for disclosure to support investor understanding of the approach the company takes to corporate governance. 

The AIM Rule changes seek to ensure that AIM companies have the flexibility to adopt governance arrangements that are appropriate to their size, stage of development and circumstances, enabling them to use a recognised code as a framework for those arrangements.

Disclosure rules

Rather than having parallel disclosure obligations under the AIM Rules and UK MAR, the AIM Rules make it clear that UK MAR sets out the general ongoing disclosure obligation for quoted companies across all UK markets, including AIM. 

The AIM Rules also state that AIM companies should seek the view of the nominated adviser on whether a change or development to their business or prospects is likely to have a material impact if made public, to support the AIM company's consideration of UK MAR.

New Express Market Route

The Designated Market Route has been replaced with a new Express Market Route, which provides a tailored and accelerated admission route for companies from a wide range of jurisdictions. The change is intended to reduce unnecessary friction for eligible international applicants, while maintaining appropriate information for investors. It is also meant to enable a broad range of international companies to benefit from it.

Osborne Clarke comment

The revised AIM Rules represent the most significant overhaul of the AIM framework in many years and reflect a concerted effort by the LSE to reposition AIM as a genuinely attractive destination for a broader range of companies. Taken together, these reforms reflect a pragmatic and market-led approach, with the LSE seeking to balance investor protection with the need to attract and retain issuers in an increasingly competitive global marketplace. 

If you would like to discuss the implications of any of these changes for your company or transaction, please get in touch with your usual Osborne Clarke contact or one of our experts listed below.