Only the LSE Main Market is fully regulated by the UK Listing Authority with detailed Listing Rules, Disclosure and Transparency Rules, Prospectus Rules etc. AIM is an exchange regulated market. Each company on AIM is required to maintain a Nominated Advisor (Cenkos then Daniel Stewart and now someone else in RIFC's case IIRC). The NOMAD is authorised by the exchange and in addition to advising and guiding the company on complying with its responsibilities under the AIM rules the NOMAD is effectively the regulator for the company's compliance. A simple placing of shares on AIM only requires an Admission Document. In RIFC's case they opted for a prospectus (under the Prospectus Rules), which facilitates issuing debt securities as well. Like all other prospectuses under the Prospectus Rules, it was submitted to the FSA (as was) for approval. That does not relieve the company and its directors of the responsibility for the information contained in the document. The boilerplate text on the Prospectus will contain something like "To the best of the knowledge and belief of the Directors and the Company (who have taken all reasonable care to ensure that such is the case), the information contained in this document is in accordance with the facts and does not omit anything likely to affect the import of such information." AIM could suspend and ultimately expell RIFC for failing to comply with the rules (and the relevant NOMADs could have their authorisation removed) but yes, it would be mainly up to the shareholders to pursue the company and directors.