1. A computer-implemented method for creating structured securities, the computer including a processor and memory, the method comprising steps performed by the computer of: creating, by the processor, a securities structure backed by mortgage pool components in accordance with structuring constraints, the securities structure having one or more classes of securities, at least one class being subject to an artificial leverage limitation under the structuring constraints because it is designated for absorbing prepayment risk; restructuring, by the processor, one of the at least one class designated for absorbing prepayment risk to overcome the artificial leverage limitation by combining it with at least one cash flow coming from interest-rate derivative components; issuing, by the processor, the structured securities.