 State ownership was to be avoided unless it was absolutely necessary for rearmament or the war effort, and even in those cases “the Reich often insisted on the inclusion in the contract of an option clause according to which the private firm operating the plant was entitled to purchase it.” However, the privatization was "applied within a framework of increasing control of the state over the whole economy through regulation and political interference," as laid out in the 1933 Act for the Formation of Compulsory Cartels, which gave the government a role in regulating and controlling the cartels that had been earlier formed in the Weimar Republic under the Cartel Act of 1923.These had mostly regulated themselves from 1923 to 1933.Companies privatized by the Nazis included the four major commercial banks in Germany, which had all come under public ownership during the prior years