Appendix C: Extended Bond Calculations
The general procedure for determining yield-to-call is as follows:
1 Store the current bond price in constant storage.
2 Determine the time portion of the yield problem as usual.
3 Divide the annual coupon rate by the call price-to-par ratio before loading it into PMT.
4 Recall the current price from constant storage and divide it also by the call price-to-par ratio, then load into PV.
5 Find the yield-to-call by pressing   i .
Example: Find the yield-to-call of a 3.25 % bond callable at 104 in 7 years now selling at 108.831895.
1 Key in 108.831895 (current price), press STO.
2 Key in 7 (yrs.), press SAVE .
3 Key in 365 (days/yr.), press × n.
4 Key in 3.25 (coupon), press SAVE .
5 Key in 1.04 (call price-to-par ratio), press ÷ PMT.
6 To recall curren t price, press RCL.
7 Key in 1.04 (call price-to-par ralio), press ÷ PV.
8 Press   i (YTM) to obtain yield, (2.40%).
To summarize:
 Enter:  See Displayed:  
  108.831895 STO 7 SAVE  365 × n 3.25 SAVE  
 
1.04 ÷ PMT RCL 1.04 ÷ PV   i   
  2.40
  % yield-to-call

Bond Amortization

Amortization of a bond premium is the gradual “writing down” of a bond investment until it reaches its face value at maturity. Conversely, for a discount bond the value is gradually "written up" until it reaches face value at maturity. The proper amortization involves the use of the same effective income ratio throughout the entire life of the bond.
The general steps to be followed are:
1 Determine the effective yield-to-maturity of the bond as of the purchase date.
2 Find the amortized value by simply applying the computed yield for the remaining time to maturity.
Example: A 4% bond was purchased at 106.75 when its time to maturity was 9 years and 10 months. What is the amortized value of the bond when it has 8 years and 11 months to maturity?
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