Marginal Cost Of Funds

The incremental cost of borrowing more money to fund additional asset purchases or investments. In its simplest calculation, the marginal cost of funds is simply the interest rate on the new loan balance. Marginal cost of funds is often confused with the average cost of funds, which would be calculated by computing a weighted-average of all the combined loans’ interest rates.

While many investors only think of the marginal cost of funds in terms of money borrowed from someone else, it's also important to think of it in terms of money borrowed from oneself or a company's own assets. In this instance, the marginal cost of funds is the opportunity cost of not investing existing funds elsewhere and receiving interest on it. For example, if a company uses $1,000,000 of its own cash to build a new factory, the marginal cost of funds would be the rate of interest it could have earned if it had invested that money instead of spending it on construction.