Money, Interest and Finance in Marx’s Capital

According to Marx, money capital, lent by its capitalist owner to an industrial capitalist, is ‘potential capital’. Interest payments made by borrowers to lenders are part of the global surplus value produced by labourers and appropriated by capitalists. There is no law of division of surplus value between profit and interest, no natural interest. Interest-bearing capital becomes a commodity sui generis. Its market price, the interest rate, is an irrational form of price. As a market price, the interest rate seems to arise from money capital as its own independent source.