Operational risk management remains a major concern for financial institutions. Indeed, institutions are bound to manage their own funds to hedge this risk. In this paper, we propose an approach to allocate one's own funds based on a combination of historical data and expert opinion using the loss distribution approach (LDA) and Bayesian logic. The results show that internal models are of great importance in the process of allocating one's own funds, and the use of the Delphi method for modelling expert opinion is very useful in ensuring the reliability of estimates. Int. J. Financial Stud. 2020, 8, 9 2 of 25 approach, the Markov chain Monte Carlo approach, and the use of copulas to model the correlation. This situation has generated a significant model risk because it has become impossible to compare and benchmark between banks and assess the evolution of the risk profile.Following the financial crisis, the minimum capital requirements for operational risk were reviewed by the Basel Committee (BCBS). Indeed, the publication in December 2017 of the document entitled "Basel III: Finalizing post-crisis reforms" divulged the orientation of banking regulation after 2022, which consists of replacing existing operational risk measurement approaches with a single approach known as the "Standardized Measurement Approach" (SMA) which will enter into effect in January 2022.The Basel committee justified the decision to abandon internal models for the calculation of capital requirements based on the complexity of the models used and proposed a simple standardized approach.Until the Basel III reform enters into effect, banks will continue to use their own models for calculating minimum capital requirements. Indeed, banks opt for two types of modelling approaches: the Top-Down approach or the Bottom-Up approach.The Top-Down approach quantifies operational risk without attempting to identify events or causes of losses. Operational losses, under this approach, are measured based on overall historical data while The Bottom-Up approach quantifies operational risk based on knowledge of events by identifying internal events and relates generating factors in detail at the level of each task and entity. The information collected is included in the overall calculation of the capital charge.Despite the Basel Committee's decision to abandon the AMA approach, the use of internal models is essential for operational risk management, notably for the risk appetite process and capital allocation process.In this study, we show the interest of internal models in the allocation of equity capital based on the LDA approach and propose a practical approach based on the Delphi method to adjust historical data by expert opinions, using Bayesian logic to determine the risk measure to be used in the capital allocation and applying the proposed approach for the allocation of capital for the retail banking business line of a Moroccan banks.Therefore, in this article, the second section will be reserved for the literature review, the third part for th...