Abstract: A common trait of laws regulating financial intermediaries and their holding companies is the attempt to separate intermediation from other business activities. In this Article, Professor Clark describes the pervasiveness of this trait and, after an analysis of the possible justifications for it, determines that separation regulation is primarily addressed to antitrust concerns and to the concern for facilitating regulation of the soundness of financial intermediaries. He argues that the first concern does not call for specialized antitrust legislation whereas the second demands that current regulation be strengthened significantly.