If the financial intermediary is not capable of managing informational asymmetries, a market failure may occur (Akerlof, 1970), and the bank may refuse to finance the customer, giving rise to the so-called credit rationing, which represents a typical adverse selection scenario where poor-quality customers drive out high-quality ones. Consequently, even if there is an excess demand for credit and customers are willing to pay a higher price (interest rate), the bank may opt not to provide financing. This decision is intended to mitigate the credit risk associated with potential deterioration in the customer’s financial situation. We analyze credit rationing models by assuming first the absence and then the existence of informational asymmetries, distinguishing between two types of models: (i) Type I rationing model, where ‘some or all customers receive a quantity of credit lower than desired at the prevailing interest rate’ (Keeton, 1979); and (ii) the more widespread Type II rationing model, where ‘banks deny credit to some customers while granting it to others who are entirely indistinguishable from those rationed’ (Keeton, 1979; Stiglitz and Weiss, 1981).