ABSTRACT
For the period from 1929 to 1950, there is no present basis for say ing whether there was an increase in concentration for non-financial corporations taken as a whole. The increase in manufacturing from 1929 to 1962 is clear. The increase for non-financial and the three sub groups after 1950 is highly probable. Also it is established that there was a very considerable increase in over-all concentration from 1929 to 1933, clearly in large part a depression phenomenon, which was pre sumably reversed between 1933 and 1939. There is little evidence that World War II changed the degree of concentration significantly. Only a careful repetition of the 1929 study can establish the changes in con centration between 1929 and 1950. Working with the available statistics makes me believe that there was not too much change in over-all con centration, though what there was was probably upward. A careful repetition of the earlier study would almost certainly find for the period 1929 to 1962 or 1965 a substantial increase, though not at anything like the rate of the 1920’s.