English Abstract: The banking sector, because of its important contribution to growth, alongside fiscal and monetary policies, is of primary interest to regulators and governments. It is the determinants of productivity that constitute a key element of analysis to provide adequate responses to banking regulation as a whole and thus to monetary policy.Up to now, research on bank profitability in Europe has mainly concerned the internal and external determinants of banks.The internal determinants involve analysing the profitability of banks based on the components of the bank's financial and accounting structure.The external determinants are indicators that take into account the economic and legal environment in which the bank operates.Other work has focused exclusively on one activity for one country, for example retail banking for the US. Others have focused on the profitability of universal banks over several countries. Recent work has focused on the stability (synonymous with soundness in our article) and therefore the risk factors of universal banks. We give some elements of apprehension of this rich literature in the introduction by integrating the most recent research on the subject. For our part, based on internal indicators, we will analyse the profitability and stability of systemic European banks from 2005 to 2013, i.e., encompassing the financial and debt crisis.This period is particularly interesting as it precedes the establishment of the European Banking Union in 2014 and is composed of two sub-periods, the pre-financial crisis and the post-financial crisis, the latter including the onset of the debt crisis. In the post-crisis stage, the European Banking Union (2014) was designed to better address the systemic risk generated by the large European banks in order to better prevent it and better solve it, in particular through bail-in mechanisms. It is therefore wise to understand what the determinants of profitability were that would justify the implementation of a banking union.We then start with an innovative algorithm method of filling in missing or partially missing data to obtain our first correlations and then we develop our causal analysis using the method of dynamic two dimensional cross-sectional panels. For each of the two methodological steps, correlation and causality, we present a rigorous analysis based on standard indicators, then new risk and activity segmentation indicators, "retail", "trading" or "interbank", to explain profitability and stability. We show that stability and profitability are common causes and often evolve in the same way from the same explanatory factors.Two major results emerge: while trading activities have a positive causal impact on profitability andstability, interbank activities have a negative causal impact on profitability and bank stability (especially until 2011 if we refer retroactively to the correlation index). The financial crisis was therefore particularly fatal to the profitability of interbank activities(synonymous with profitability in our article) according to the correlation index. In our article, causality does not allow us to establish a change in the contributing factor. The result on trading activity seems rather surprising to us because if we had limited ourselves to an analysis in terms of correlation, considering it to be causality, we would have obtained the opposite result: a strong negative impact in the wake of the financial crisis, less so afterwards. Correlation therefore sheds light on causality and its strength, but should not be confused with causality, which assumes a different method of correlation. After this point of statistical insight, we turned to the subject of bank profitability and stability
