Assuming that a firm's opportunity cost is its Weighted Average Cost of Capital , any investment in working capital that does not generate sales or improve the operating margin results in capital tied up in operations that generates no rate of return. The present value of such an investment should be discounted at the cost of capital; this would be the sum of an infinite series, which equals the initial investment, delta operating working capital , that would grow at the same rate as the growth in revenue, g. This hypothesis is trivial at first; however, unlike other types of investments, it does not depreciate at any rate. It can only be recovered by streamlining operations, which yields this amount back into cash holdings, or n days after the company ceases its operations, where n is days sales outstanding.