Salem, you can look to the works of Xavier Freixas about banking theory.

https://mitpress.mit.edu/sites/default/files/titles/content/9780262062701_sch_0001.pdf

https://mitpress.mit.edu/books/microeconomics-banking

I heard his lectures in the university.

Profitability of bank clearly depends on the competition among banks. But even bank-monopolist can make losses if it has bad credit policy and low risk diversification.

Thank you so much

You might want to check out this paper

Article Marx's Analysis of the Relationship between the Rate of Inte...

You should also look at Grifell-'Tatje & Lovell (1999) in Management Science

I would look at the paper:

Ho, T., Saunders, A., 1981. The determinants of bank interest margins: theory and

empirical evidence, Journal of Financial and Quantitative Analysis 16, 581--600.

Good Luck

Thank you so much

https://www.researchgate.net/publication/305815587_The_Dhaka_Mercantile_Co-operative_Bank_Limited_A_Case_of_Islamic_Shari%27ah_Banking_in_Bangladesh

Article The Dhaka Mercantile Co-operative Bank Limited: A Case of Is...

You may find answer from here.

https://www.researchgate.net/publication/346464096_Determinants_of_Profitability_A_Study_on_Manufacturing_Companies_Listed_on_the_Dhaka_Stock_Exchange?_sg=started_experiment_milestone