Insider dealing has been in the public eye for many years now. The impact of Big Bang and the growth of financial conglomerates has, however, propelled the practice to the very forefront of regulatory concern. Regulators are faced with a dilemma: financial conglomerates bring with them many economic benefits, but they also accentuate the problem of insider dealing, in that the greater availability of inside information within these open ended financial houses, increases the scope for its misuse. Regulators must ensure that the regulation imposed does not overly impede the benefits to be gained from conglomeration; yet they must ensure that regulation is sufficiently stringent to provide a fair market place. The Chinese Wall - a self-styled mechanism consisting of policies procedures designed to stop the flow of inside information within financial conglomerates - is singled out for special treatment. The legal and policy problems associated with the use of the mechansim are reviewed. These revolve around two main issues: (i) Is the Wall an effective policy device to rebut allegations of insider dealing in a financial conglomerate where Arm A is dealing in shares in Company X while arm B has information pertaining to Company X. (ii) If the Chinese Wall actually works, does the operation of the mechanism give rise to breach of fiduciary obligations ie. to what extent does the operation of the Chinese Wall in conglomerates modify traditional fiduciary law. The conclusion reached is that the Chinese Wall offers regulators the best solution to the problem of conflicts of interest and obligation in fully fledged financial conglomerates. The Wall must, however, be 'strengthened' to prevent, for example, a coroprate fiduciary dealing for its own account where another department within the conglomerate has a material interest in the transaction. At common law, the courts ought to, and probably would, accept this approach. However in an action brought under the SIB rulebook, and the rulebooks made thereunder, it would seem that the courts are bound to accept a Wall per se (ie. without being strengthened) as valid. To the extent that this differs from what ought to be the position at common law, the SIB rulebook should be modified. A tentative import of economic analysis is used to complement the largely legal analysis. In this way it is hoped to gain a better grasp of the policy issues under study.