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I don't get how to do this one, is a bond similar to compounding interest?

  • A "vanilla" bond is a fixed-rate instrument. At the end of each coupon period, it pay an interest according to a pre-agreed interest rate and a fixed principal. It behaves more like a simple interest rather than a compounding interest. – achille hui Feb 02 '14 at 06:49
  • fixed principial - the face value? – terrible at math Feb 02 '14 at 08:16
  • yup, same as face value. – achille hui Feb 02 '14 at 08:21
  • this problem seems too simple - wouldn't the zero rate for bond 1 be 6% and bond 2 8%? – terrible at math Feb 02 '14 at 08:23
  • @achillehui

    probably not, so ive been thinking about it some more..

    it pays 6 dollars (6% of 100, its FV) 2 times a year, so in 5 years it will give100 + (10*6) = 160

    how do i use the selling price though? (95 dollars)

    – terrible at math Feb 02 '14 at 08:33
  • zero rate is the effective rate for a bond with zero coupon payment. You can synthesis a zero coupon bond by creating a portfolio longing 4 units of bond 1 and shorting 3 units of bond 2. – achille hui Feb 02 '14 at 08:43
  • I have no idea what you mean by portfolio. based on what you said, is it the first 4 payments of bond 4 minus the first 3 payments of bond 2? – terrible at math Feb 02 '14 at 08:45
  • If you don't know what a portfolio is, you have no way to understand why the final answer work. You need to look that up and understand that concept first. – achille hui Feb 02 '14 at 08:49
  • heh, im trying now but apparently google searching isn't very good for finance stuff.

    The hint it gives makes little sense to me.. "receives no payments until five years from now"

    why would we ignore the coupon though?

    – terrible at math Feb 02 '14 at 08:58
  • You are not ignoring the coupon. You buy & sell in appropriate quantities so that the net coupon is zero. – copper.hat Feb 02 '14 at 09:22
  • @copper.hat can you explain what you did below? – terrible at math Feb 02 '14 at 17:21

1 Answers1

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Perhaps I am missing something, but it would see to me that you could buy ${8 \over 14}$ of the #1 bond and sell ${6 \over 14}$ of the #2 bond for a net cost of ${8 \over 14} 95 - {6 \over 14}97 \approx 12.71$. Then the semi-annual payments would be zero (since ${1 \over 2} ({8 \over 14} 0.06 - {6 \over 14}0.08) = 0$), and the value after 5 years would be ${8 \over 14} 100 - {6 \over 14}100 \approx 14.29$.

Then solving $(1+r)^5 = {14.29 \over 12.71}$ gives $r \approx 2.4$%.

(This assumes that you can short the bond, of course.)

The following table illustrates the idea, I have used integral units of stock to simplify. \begin{array}{c|ccccccccccc} \text{cash flow}& 0 & 1 & 2 & 3 & 4 & 5 & 6 & 7 & 8 & 9 & 10 \\ \hline \\ \text{buy 8 #1} & -760 & & & & & & & & & & 800 \\ & & 24 & 24 & 24 & 24 & 24 & 24 & 24 & 24 & 24 & 24 \\ \text{sell 6 #2} & 582 & & & & & & & & & & -600 \\ & & -24 & -24 & -24 & -24 & -24 & -24 & -24 & -24 & -24 & -24 \\ \hline \\ \text{net} & -178 & & & & & & & & & & 200 \\ \end{array}

Hence $r = \sqrt[5]{{200 \over 178}}-1 \approx 2.35\%$.

copper.hat
  • 172,524
  • I should have used whole numbers above... – copper.hat Feb 02 '14 at 09:14
  • how did you figure this out? I'm a bit lost. – terrible at math Feb 02 '14 at 17:20
  • The #1 bond pays 6% pa. and the #2 bond pays 8% pa. To get a zero coupon payout, I must (in this case) buy an appropriate quantity of the #1 bond and sell an appropriate quantity of the #2 bond so that the payments cancel. If I buy 8 #1 bonds, my yearly coupon will be $$8 \cdot 6$ and if I sell 6 #2 bonds, I will need to pay out a yearly coupon of $$6 \cdot 8$, so they match. Then the net transactions are the initial buying/selling of the bonds and the final payout. – copper.hat Feb 02 '14 at 18:05
  • pa = per annum? doesn't it say semiannually? – terrible at math Feb 02 '14 at 19:07
  • The question also says 'per annum, paid semi-annually' (fairly typical for bonds). In this case it doesn't matter, as we are matching the net coupon payments, so the rates are used purely to compute the matching coupon payments. – copper.hat Feb 02 '14 at 19:26
  • I would suggest writing out a time line with $0,...,10$ as the axis, and write out the number for buying 8 #1 bonds and selling 6 #2 bonds on separate lines. Then add the columns to get the net payments. – copper.hat Feb 02 '14 at 19:30
  • this is a lot more complicated than i expected, i find it funny that im better at abstract algebra than this. i will practice. – terrible at math Feb 02 '14 at 19:33
  • I added a table above to illustrate the idea. I find the ideas straightforward, but the nomenclature confusing. – copper.hat Feb 02 '14 at 19:52
  • thanks a lot for this, i am sure i will figure it out now, that is fantastic. – terrible at math Feb 02 '14 at 19:58
  • The coupon payment is off. For 8 units of bond at rate 6% ( quoted in 'per annum' convention) paying coupon semiannually. The coupon paid at end of each period is $$ 8 \times $100 \times 6% \times 1/2 = $24 $$ – achille hui Feb 02 '14 at 20:04
  • @achillehui: You are correct, thanks for catching that. I will fix it. I had a few other related issues, all because I know the net coupon payment is zero anyway. – copper.hat Feb 02 '14 at 20:17
  • @copper.hat hey man thanks so much, i did it myself and got it and understood it :) could you provide the formula that you used to calculate the zero rate though? its familiar but im forgetting – terrible at math Feb 02 '14 at 21:23
  • It you start with principal $P_0$ and invest it for $n$ years at a fixed annual rate $r$ then after $n$ years it will have value $P_n=P_0(1+r)^n$. To given $P_0,P_n$, you can figure out an equivalent yearly rate by solving the equation for $r$, that is, $r = \sqrt[n]{{P_n \over P_0}} -1$. – copper.hat Feb 02 '14 at 21:32
  • I see, so it's the familiar form that I'm used to, just this $P_n$ that's new. We don't care about the negative sign on our $P_0$ in this case? – terrible at math Feb 02 '14 at 22:00
  • Well, no, that's cash flow, so you purchase the bond (money leaves your wallet) and at the end you receive a payment (money enters your wallet). So $P_0 = |\text{outgoing}|$ and $P_n = |\text{ eventual return}|$. – copper.hat Feb 02 '14 at 22:07
  • I see. We also sold bonds in this example, so that means we can owe money too, right? – terrible at math Feb 02 '14 at 22:44
  • Well, you could, but you would not choose a portfolio if the net return was negative. In this example, the net return is 2.35% after the final sell/buy, so this is a gain. – copper.hat Feb 03 '14 at 03:56