For UK listed companies, communication with the market is not optional, it is a legal duty. From inside information to periodic financial reports, from major transactions to takeover leaks, the framework is detailed and tightly policed. This blog gives a clear guide to the rules, focusing on what UK companies must announce, how they must do it, and why disclosure discipline matters.
The UK Disclosure Framework
The main rulebooks are the
UK Market Abuse Regulation (UK MAR), the FCA’s
Disclosure Guidance and Transparency Rules (DTRs), and the new
UK Listing Rules (UKLR). AIM companies follow the
AIM Rules. During takeovers the
Takeover Code applies.
Announcements must be released through a Primary Information Provider, usually the London Stock Exchange’s
RNS. Certain documents, like annual reports and circulars, must also be stored on the FCA’s
National Storage Mechanism (NSM).
The UK system is disclosure-driven: the market, not the regulator, decides what to make of the information. That means clarity and completeness are vital.
Inside Information and When to Announce
The most important trigger is inside information. Under
UK MAR Article 7, information is inside if it is precise, non-public, relates to the company, and would likely affect the share price.
Once inside information exists, it must be announced “as soon as possible” under
Article 17. Companies can only delay if disclosure would harm legitimate interests, delay would not mislead the market, and confidentiality can be maintained. If delay is used, records must be kept and the FCA notified once disclosure happens.
Leaks and rumours are a common risk. If speculation is accurate or the share price moves abnormally, the safest response is a holding announcement. Boards should keep tight control over who knows what, maintain insider lists, and ensure records are complete.
Financial Reporting and Closed Periods
Companies face a set reporting calendar under
DTR 4. Annual financial reports must be published within four months of year end, half-yearly reports within three months. Reports must be released through a RIS and filed on the NSM, and remain accessible for at least ten years.
Closed periods restrict trading by directors and senior managers. Under
Article 19 of UK MAR, they cannot deal in company shares during the 30 days before annual or half-yearly results. Exceptions are very limited. Boards should maintain strict dealing codes and clear trading windows.
PDMR Dealings and Notifications
Persons Discharging Managerial Responsibilities (PDMRs) and their closely associated persons must notify dealings in company shares. Notifications must be made within three business days, and the company must announce the transaction within the same period.
The FCA provides the
electronic form for these Article 19 notifications. Companies should treat each PDMR trade like a compliance project, checking closed period status, clearing the trade, and preparing the RIS release.
Major Shareholding Notifications
Investors must notify when their holdings cross 3 percent or each whole percentage above, under
DTR 5. They use the
TR-1 form, which the company must then announce via RIS within two trading days.
Issuers must also publish “total voting rights” announcements whenever the share capital changes. This ensures investors can calculate if thresholds have been crossed. AIM companies follow
AIM Rule 17, which requires similar notifications for holdings of 3 percent or more.
Significant and Related Party Transactions
The UKLR introduced in 2024 changed how transactions are handled. Deals where a class test exceeds 25 percent must be announced, but shareholder approval is no longer usually required unless the transaction is a reverse takeover.
Related party transactions remain stricter. If a deal with a related party exceeds 5 percent on any class test, a RIS announcement must be made, including a statement that the terms are fair and reasonable, confirmed after consulting a sponsor. See
UKLR 14 for detail.
For AIM companies, the AIM Rules (12 to 14) set out equivalent requirements, with shareholder votes still required in some cases.
Takeover Code and Leak Announcements
When an offer is on the table, the
Takeover Code takes over. Rule 2 requires announcements when an offer is imminent, a bidder is identified following speculation, or the share price moves unexpectedly.
Once a potential bidder is named, the 28-day “put up or shut up” period begins. During this time the bidder must either announce a firm offer under Rule 2.7 or walk away. The Takeover Panel polices all announcements for accuracy, with directors and advisers personally responsible.
Leak announcements are common. The Panel’s
Practice Statement 20 explains when they must be made. Coordination with MAR is key, since both regimes apply at once.
Dissemination, RIS, NSM and Investor Access
How announcements are made matters. Issuers must use a
Primary Information Provider such as RNS, and classify announcements under the right headline codes.
The
NSM is the official archive, and company websites must also carry regulatory information for at least five years (ten for financial reports). AIM Rule 26 sets additional website requirements.
Best practice is to release through RIS, update the company website, and file to the NSM simultaneously. Clear, plain language helps all investors, retail and institutional alike.
Conclusion
Disclosure is the backbone of trust in UK markets. Companies cannot treat announcements as box-ticking. Boards must build cultures, systems and controls that deliver timely, accurate and accessible information. From inside information to major transactions and takeovers, the market expects clarity, and the regulators will act if standards slip.
For UK listed and AIM companies alike, good disclosure is good governance.
