Commentary: Rules make it hard to tell what directors are meant to reveal

In the 15 days since Carphone Warehouse disclosed that its deputy chairman, David Ross, had pledged his £157 million stake in the firm against personal loans, City lawyers have been rushing to reassess their advice to clients who are directors of public companies.

That, it is understood, is why Michael Spencer told his friend Oliver Hemsley (they are respectively chairman and chief executive of Numis) about his use of Numis shares to back up loans to his private company. Spencer's lawyers, who originally felt there was no need for disclosure, changed their minds following the Ross witch-hunt.

None of this is easy. Numis is listed on AIM, not the main market. AIM rules are enforced by the London Stock Exchange, not the Financial Services Authority. AIM is also generally considered to be regulated with a lighter touch. But a glance through the rules shows AIM levels of disclosure are as, or more, strict than for a fully listed company.

There is still confusion. What did Spencer want the loan for? Did he offer to resign as Numis chairman if he felt he broke the rules? Spencer has regularly made disclosures about his shares in Icap. He disclosed in September that £45 million worth of them, held by the same subsidiary of his private interests, were used in a deal with JPMorgan.

It is unclear whether the rules mean that when shares are used as security, it needs full public disclosure through the Stock Exchange or just privately to the company chairman.

The Ross affair has rattled many cages. The FSA and the Stock Exchange are making louder noises. There are almost certainly hundreds of directors who have, legitimately, pledged shares in their own companies against loans.

Come the New Year and the regulators should clarify what the rules mean. They won't put it that bluntly because that would mean admitting they were unclear in the first place. But you have been warned.