Operational risk is a big concern for financial firms due to significant losses in the past decade. Unlike other risks, there are limited tools to analyze and quantify operational risk. The Basel II framework allows banks to create their own risk assessment models, like the Advanced Measurement Approaches (AMA). This paper explores using the AMA to calculate operational risk capital charges for banks and insurance companies under Basel II and U.S. regulations. The AMA in the study uses actuarial loss models and extreme value theory to determine the probability distribution of capital charges. Real operational risk loss data is used for the analysis.