Yield maintenance is a kind of prepayment fee that borrowers pay to lenders or bond issuers to investors to compensate for the loss of interest resulting from prepaying a loan or calling a bond.
Yield maintenance is designed to reduce the risk of prepayment by creditors or to prevent early repayment of debt by borrowers.
The formula for calculating the premium for maintaining profitability: Maintaining profitability = Present value of remaining mortgage payments x (interest rate - treasury income).