Let's go by parts.>Fascist Italy saw the complete dominance of monopoly capitalism
It would be more accurate to say that Fascist Italy saw a complete monopoly of the State over capital:
"In the course of its developmental and autarchic program, in 1937, the Fascist government declared the IRI a permanent parastate agency. By that time the lstituto controlled over forty-four percent of all Italian capital stock, and almost eighteen percent of the total capital of the nation. For all intents and purposes, the credit system of the nation was under the control of state and parastate agencies. By the end of the 'thirties, approximately eighty percent of the credit available in the Italian economy was controlled directly or indirectly by the state.68 The Fascist government had developed more elaborate controls over the economic enterprise of the nation than any other state of the period save the Soviet Union" (A. James Gregor).
>Banking cartels were integrated into the state
"In the face of the international situation the Fascist government increased its legislative controls over the financial institutions of the peninsula. The centralization of banking
to which Borkenau later alluded was begun during 1926. By the fall of 1926 a government Istituto di Emissione became the central agency for the issuance of national currency"-
(A. James Gregor).
It would have had no sense that Mussolini allowed banking cartels to thrive, yet took away from them the right to issue national currency. It does not make sense, either, that the lstituto per la ricostruzione industriale, being an state agency, became the principal credit institution; nor that through this same institution was the Fascist government able to de facto nationalize all banking industry.
Before the advent of Fascism, the principal banking association was the Associazione Bancaria Italiana. Instead of letting this association be independent and determine the development of the banking industry, the Fascist régime established the General Fascist Banking Confederation, which gave the industry new responsibilities under the syndical state: "The Syndical Section became officially responsible for a programme that was almost entirely new as compared with that carried out by the previous Banking AssociaPost too long. Click here to view the full text.