What it means
The mechanics mirror share options, with one important twist. The underlying asset is a bond whose price is quoted as a percentage of face value, so a strike price of 98 means the right to trade at 98% of the bond's par amount rather than at 98 dollars.
Options are used for two very different jobs. Speculators buy calls when they expect rates to fall and bond prices to rise, while treasurers and fund managers buy puts as insurance against a portfolio falling in value if rates climb.
The buyer's downside is capped at the premium paid, which is the feature that makes options attractive to risk-conscious finance teams. The seller, or writer, collects that premium up front and takes on an open-ended obligation if the market moves the wrong way.
Bond options come in listed and over-the-counter forms. Exchange-traded options usually sit on government bond futures and are highly standardised, while over-the-counter contracts are negotiated directly with a bank and can be tailored to a specific bond, size and date.
Two close relatives cause confusion. An embedded option is baked into a bond itself, as in a callable bond where the issuer effectively holds a call, and a swaption is an option on an interest rate swap rather than on a bond.
Time is the option buyer's enemy. Every day that passes without the expected move erodes the option's value, so being right about direction but wrong about timing still loses money.
In practice
Real-world examples.
Example
A pension fund expects central bank rate cuts within six months and buys call options on government bond futures rather than buying the bonds outright. The options cost a fraction of the cash outlay, so the fund keeps most of its money available while still positioned for a rally.
Example
An insurer holding a large corporate bond portfolio worries about a rate rise before its year-end reporting date. It buys put options as protection, accepting the premium cost as the price of a floor under the portfolio's reported value.
Example
A bank writes covered call options against bonds it already owns, collecting premium income each quarter. The trade-off is that if prices rally sharply the bonds get called away and the bank misses the upside above the strike.
Formula
Calculation
Call payoff at expiry = max(0, market price - strike price) x face value / 100
Net profit = payoff - premium paid
An investor buys a call option on a corporate bond with $100,000 of face value, a strike price of 98 and a premium of 1.20 points. The premium in cash is $100,000 x 1.20 / 100 = $1,200.
Interest rates fall and at expiry the bond is trading at 101.50. The payoff is (101.50 - 98) x $100,000 / 100 = 3.50 x $1,000 = $3,500, and the net profit is $3,500 - $1,200 = $2,300.
The break-even price is the strike plus the premium, or 98 + 1.20 = 99.20. If the bond had finished anywhere at or below 98 the option would have expired worthless and the loss would have been the full $1,200 premium, no more.Case study
Seen in the real world.
The following is an illustrative and entirely fictional example. Quillfield Mutual, an invented insurance company, held $5,000,000 of face value in long-dated corporate bonds and faced a solvency test at the end of the year. Its investment committee judged that rates might rise, which would push the bonds' market value down at exactly the wrong moment.
Rather than sell the bonds and lose the coupon income, the committee bought put options with a strike price of 95 at a premium of 0.80 points. The cash cost was $5,000,000 x 0.80 / 100 = $40,000, which the committee treated as an insurance expense rather than an investment.
Rates rose and the bonds fell to 91 by expiry. The put paid (95 - 91) x $5,000,000 / 100 = 4 x $50,000 = $200,000, giving a net gain of $200,000 - $40,000 = $160,000 that offset most of the fall in the portfolio's value. Had rates instead fallen, the fictional insurer would simply have lost the $40,000 premium and enjoyed the rise in its bonds.
Watch out
Common mistakes.
- Reading the strike price as a dollar amount rather than a percentage of face value, which understates the size of the position by a factor of a thousand or more.
- Ignoring time decay and holding an option too long, so a correct view on rates still ends in a total loss of premium.
- Writing uncovered options for the premium income without modelling the loss if the market moves sharply against the position.
Questions
People also ask.
Is a bond option the same as a callable bond?
No. A callable bond contains an option that belongs to the issuer, whereas a bond option is a separate contract you buy or sell in its own right.
Why do bond prices and interest rates move in opposite directions?
A bond pays a fixed coupon, so when new bonds offer higher rates the older, lower-paying bond must fall in price to remain competitive.
What is the most you can lose buying a bond option?
The premium you paid, which is why buying options is often described as a defined-risk way to express a view on interest rates.
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