Abstract: Systems and methods are provided that allow a financial instrument to be structured so that the underlying borrowed principal is callable, putable, or both. In one example, a Range Accrual Mortgage is structured so that the underlying borrowed principal is a mortgage that is callable, putable, or both by embedding into the loan structure a rate put option, and by permitting correlative adjustments to the outstanding loan principal. The invention lends symmetry to the interest rate behavior of certain borrowings by making explicit the pricing and market value of options that were previously only implicit in the borrowing structure. For example, a mortgage in accordance with the invention should provide incentives for either the homeowner or the bank to refinance the mortgage and should do so whether interest rates rise or fall, and no matter what path interest rates follow from the inception of the instrument until its maturity.