AIM Rules for Companies: New Rules Now in Effect

Following the consultation that closed on 2 July 2026, the London Stock Exchange has now published the new AIM Rules for Companies.

The majority of the changes set out in the consultation have been adopted in materially the form proposed. By way of brief recap, the key changes now in effect include:

• the replacement of the working capital statement with a capital resources disclosure;
• the increase of the substantial transaction threshold from 10% to 25%;
• the removal of the 100% class test limb from the reverse takeover definition;
• the replacement of Rule 11 with a new “Ongoing Developments” obligation;
• the permission for UK GAAP reporting and the abolition of “comply or explain” corporate governance in favour of a disclosure-based approach;
• the introduction of dual-class share structures;
• the new Express Market and dual market applicant admission routes;
• the Capital Access Window; and
• the voluntary right of reply to third party commentary.

Please refer to our previous article for further details.

Below, we focus on some of the other key principles confirmed in the new rules.

Key points to note

1. Express applicant eligibility criteria confirmed
   
    The new rules codify specific thresholds for Express Applicants:
   
   • at least 3 years' trading on an Express Market;
   
   • no fundamental change to business or board in the last 12 months;
   
   • proposed market capitalisation of at least £20 million on admission to AIM; and
   
   • all admission documentation and required disclosure published in English.
2. Accounting flexibility now broader
    
   UK companies are permitted to use UK GAAP instead of IFRS. The LSE may permit other local GAAPs where IFRS equivalency is demonstrated.
3. Nomad's view described as “authoritative”
    
   The published guidance confirms enhanced influence such that a nomad's view on market impact is to be “considered authoritative” and that the nomad is not required to provide the AIM company with a formal or detailed supporting analysis in support of that view.
4. Lock-in exemptions for substantial shareholders
    
   The guidance to Rule 7 confirms that certain categories of substantial shareholder are not required to be subject to a lock-in. 
    
   These categories (e.g., authorised persons and externally managed investing companies) substantially replicate exemptions that previously existed as carve-outs from the definition of “substantial shareholder” in the old rules. 
    
   The practical significance of this change is that these entities are now treated as substantial shareholders (and therefore related parties) for all purposes, including Rule 13 related party transactions, while retaining their Rule 7 lock-in exemption (see item 9 below).
5. Capital Access Window – cleansing notification mechanism
    
   The new rules require “a cleansing notification being made, either confirming that the fundraise or corporate transaction involving the issue of AIM securities has completed or that it has aborted”.
6. Suspension for Disclosure – new named category
    
   A formal “Suspension for Disclosure” category has been introduced alongside the Capital Access Window, codifying pre-existing practice for companies needing time to establish facts before notifying the Exchange (e.g., financial difficulty).
7. Fundraise participation exemption
    
   Director or substantial shareholder participation in a fundraise will not constitute a related party transaction (and no fair and reasonable statement is required) provided:
   
   • participation is on the same terms as other investors; and
   
   • the price is set by (i) directors not participating in the fundraise or (ii) agreement with an investor (or investors) who is not a related party (as defined in the rules).
8. Expanded related party definition

   Two new limbs have been added to the “related party” definition: 
   “(d) any company where one or more of its directors is also a director of the AIM company; and (e) any person holding a 10% interest or more in an AIM company's subsidiaries and/or assets.” 

   (Lettering reflects the structure of the new rules definition.)

9. Relocation of substantial shareholder carve-outs and broadening of the related party transaction regime
    
   Under the previous rules, the definition of “substantial shareholder” excluded authorised persons, externally-managed investing companies, and Exchange-quoted companies (for the purposes of Rule 7). 
    
   These carve-outs have been removed from the definition itself, with the result that these entities are now treated as substantial shareholders and therefore as related parties for all purposes under the rules. This includes Rule 13 related party transactions.
10. Exclusion of third-party rights
     
    The new rules include a blanket statement: “No rights are provided to or actionable by third parties under these rules.” 
     
    Rule 1 additionally states that nominated adviser obligations “are owed solely to the Exchange” and “are not actionable by third parties”, thus providing a significant legal shield for the Exchange and nominated advisers against private claims.
11. Reverse Takeover Cancellation timing
    
    Cancellation of AIM securities following a reverse takeover now occurs “upon completion of the acquisition” rather than when shareholder approval is given.

The new AIM Rules for Companies took effect on 5 August 2026.

We would be happy to discuss the implications of these changes for AIM companies, nominated advisers, and prospective applicants.

Client Alert 2026-160