The internal rate of return (IRR) is the gold standard for normalizing and comparing returns across different investments. Generally, it refers to the discount rate at which the present value of all of an investment’s cash flows, including the purchase price and every incoming and outgoing payment, equals zero. For lending, IRR measures profitability: negative means a loss, zero is breakeven and positive is a gain. See also Yield. LoanStreet Analytics calculates IRR for loans, pools and portfolios as part of its loan return analytics.