Absolute overaccumulation of capital with the size of population and technology held constant

Marx says:

Take a certain working population of, say, two million. Assume, furthermore, that the length and intensity of the average working day, the level of wages, and thereby the proportion between necessary and surplus labour, are given. In that case the aggregate labour of these two million, and their surplus labour expressed in surplus value, always produces the same magnitude of value. (1959, pp. 216—17)

Under these presuppositions capital accumulation runs up against a maximal limit which can be calculated exactly because the maximum amount of surplus value obtainable is exactly given. It would make no sense to continue accumulation beyond this limit because any expanded capital would yield the same mass of surplus value as before. If accumulation were continued it would necessarily lead to a devaluation of capital and a sharp fall in the rate of profit:

a portion of the capital would lie completely or partially idle (because it would have to crowd out some of the active capital before it could expand its own value), and the other portion would produce values at a lower rate of profit owing to the pressure of unemployed or but partly employed capital ... The fall in the rate of profit would then be accompanied by an absolute decline in its mass ... And the reduced mass of profit would have to be calculated on an increased total capital. (1959, p. 252)

This constitutes a case of absolute overaccumulation of capital ‘because capital would be unable to exploit labour ... to the degree which would at least increase the mass of profit along with the growing mass of employed capital’ (p. 255). According to Marx this would be the case ‘in which more capital is accumulated than can be invested in production ... This results in loans abroad, etc. in short, to speculative investments’ (1969, p. 484).