We rationalize the organization of US banking groups into a holding company with subsidiaries – instead of branches or stand-alone units – subject to regulatory provisions of the ”source-of strength” type. We show that their value increases with debt diversity among affiliates and with complexity, as measured by the number of subsidiaries. Regulatory interventions that are aimed at ring fencing reduce (increase) the shareholder value, whenever the Governmental leniency to bailout is low (high). Branches become more valuable when there is no full commitment to internal rescue and Government bailout occurs with certainty.