effective yield
Effective yield is the true return on a bond once you count compounding, showing what your money actually earns, more than the sticker rate.
In plain English
The day NEPA brought light back after a week of darkness, our street generator man still made his rounds collecting money, because he had been calmly running a smaller line to a few houses who paid him daily instead of monthly. Same generator, same fuel, but the daily payers were effectively paying him more per month than the ones who paid once, because their money kept flowing back to him and he kept redeploying it.
Bonds work the same way. A bond might advertise a coupon rate of say ten percent a year, and that sounds fixed and final. But if that bond pays interest twice a year instead of once, and you reinvest each payment, your actual return by year end is higher than ten percent, because the interest you received in June has spent six months earning its own interest before December arrives.
That real number, the one that accounts for how often interest is paid and reinvested, is the effective yield. The coupon rate is the promise on paper. The effective yield is what actually lands in your account once compounding has done its calm work.
A Nigerian civil servant buying FGN savings bonds through her stockbroker sees a coupon rate advertised, but if she wants to know what she truly earns over the life of the bond, she has to check the effective yield, especially if interest is paid quarterly. Someone in London holding a UK gilt faces the same gap between the coupon printed on the bond and the effective yield once semi annual payments are reinvested.
For anyone sending money home to invest in Nigerian bonds on behalf of family, this number matters more than the advertised rate, because it tells you what the investment is really doing, more than what it promised to do.
A bond has a face value of ₦1,000,000 and a coupon rate of ten percent paid twice a year, so ₦50,000 every six months. If you reinvest each ₦50,000 payment at the same rate, by year end you have earned slightly more than ₦100,000 in total, giving an effective yield just above ten percent, even though the coupon rate stayed exactly the same on paper.
Questions people ask
Is effective yield the same as coupon rate?
No. The coupon rate is the fixed percentage printed on the bond. The effective yield adjusts for how often interest is paid and reinvested, so it usually ends up higher than the coupon rate when payments happen more than once a year.
Why does effective yield matter if I am not reinvesting the interest?
If you spend the interest as it comes rather than reinvesting it, your actual return will be closer to the coupon rate, not the effective yield. Effective yield assumes reinvestment, so it matters most to investors who plan to compound their returns.
How do I calculate effective yield myself?
Take the coupon rate, divide by the number of payments per year, add one, raise that to the power of the number of payments per year, then subtract one. It sounds fiddly, but most bond calculators and stockbrokers will show you this figure directly.
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