Suppose you narrow your spread and then stock out. What is the opportunity cost of one month of missed sales? (Remember, your fixed costs were already covered by the sales you did make. Therefore, an additional month of sales would only incur the cost of goods. No marketing, R&D, or depreciation expense are felt because those have already been paid for by the units you did sell. Even the Interest payments have been made.) For example, if your sales were $120M, in one month you sell $10M. If a months material and labor costs are $7M, you missed contributing $3M to Net Margin. This would be taxed in the simulation at 35%, so your opportunity cost is a missed $2M in profit.