Can you help explaining the the reason of why issuing a mortgage loan is like issuing a bond and then write a call option on the principle of the loan?
In simple terms, as I see it ---> Mortgage loan similar to coupon bond in that mortgagor receives monthly interest + principal repayments, as opposed to a bullet maturity. i.e. there is a regular cash inflow.
Similar to american call option from point of view of mortgagee (buyer of option as I see it), in that they have the right to repay the mortgage at any time. i.e. to call the debt in.