Regulatory stacking occurs when organizations must simultaneously comply with federal, state, local, and international rules governing similar risks, often with inconsistent requirements or timelines. This creates operational complexity, increases compliance costs, and elevates the risk of inadvertent violations. Financial services firms frequently face stacking across banking, securities, consumer protection, and data privacy regimes. For instance, multinational banks must reconcile GDPR, CCPA, and dozens of other privacy laws while maintaining unified customer data systems, requiring sophisticated compliance architectures and legal interpretation.