Bond Fundamentals
The Global Bond Market
- Global bond market ≈ $120 trillion — larger than global equity markets (~$100T)
- Bonds are the primary financing tool for governments and investment-grade corporations
- Bonds are debt: the issuer borrows, pays periodic interest (coupon), and repays principal at maturity
Bond Terminology
| Term | Definition |
|---|---|
| Face Value / Par | Principal amount repaid at maturity (typically $1,000) |
| Coupon Rate | Annual interest as a % of face value; fixed at issuance |
| Coupon Payment | = Coupon Rate × Face Value (paid semi-annually in North America) |
| Maturity | Date principal is repaid; term = years to maturity |
| YTM (Yield to Maturity) | IRR of the bond — discount rate that makes PV of all cash flows = market price |
| Current Yield | Annual coupon / current market price (ignores capital gains) |
| Premium Bond | Coupon rate > YTM → price > par |
| Discount Bond | Coupon rate < YTM → price < par |
| Par Bond | Coupon rate = YTM → price = par |
Types of Bonds
Bond Pricing & YTM
Zero Coupon Bond Pricing
PV = 1,000 / (1.06)^5 = $747.26
Coupon Bond Pricing
Example 1: Premium Bond
Example 2: Discount Bond
Semi-Annual Coupon Bonds (Standard in North America)
C = $25 per period; n = 20; r = 3%
B = 25 × [1−(1.03)^-20/0.03] + 1,000/(1.03)^20 = $925.61
(Slightly different from annual due to more frequent compounding)
Solving for YTM
YTM is the IRR of a bond — the single discount rate that equates the PV of all future cash flows to the current market price.
There is no closed-form algebraic solution for YTM in coupon bonds — must be solved iteratively (trial and error, financial calculator, or Excel).
Bond Price Dynamics & Volatility Rules
Six Bond Price Volatility Rules
Bond prices move inversely to interest rates (YTM). When yields rise, prices fall; when yields fall, prices rise. Coupon > YTM → premium; Coupon < YTM → discount; Coupon = YTM → par.
For a given change in yield, longer maturity bonds have greater price sensitivity than shorter maturity bonds. The further into the future cash flows occur, the more heavily they are discounted by a rate change.
Price sensitivity to yield changes increases with maturity, but at a decreasing rate. Going from 1yr to 5yr adds much more sensitivity than going from 20yr to 25yr.
For the same maturity, lower coupon bonds have greater price sensitivity than higher coupon bonds. A zero coupon bond is maximally sensitive — all cash flow is at maturity.
For equal yield changes up and down, price appreciation exceeds price depreciation. This asymmetry (convexity) benefits bondholders — the price-yield curve is convex, not linear.
Price sensitivity to a given yield change is greater at lower initial yields than at higher initial yields. A 1% fall from 2% has a bigger impact than a 1% fall from 8%.
Yield Spread
Definition: YTM(corporate) − YTM(government bond of same maturity). Compensates investors for default risk above the risk-free rate.
| Market Environment | Spread Direction | Reason |
|---|---|---|
| Recession / pessimism | Widens ↑ | Higher perceived default risk; flight to quality (govt bonds rally, corps fall) |
| Expansion / optimism | Narrows ↓ | Lower perceived risk; credit demand for corporate bonds compresses spreads |
| Investment Grade (BBB) | Narrowest IG spread | Still considered safe; traded actively by pension funds |
| High Yield (BB and below) | Wide | Significant default risk premium required |
Duration & Immunization
Duration — Definition & Calculation
Duration is the weighted average time to receipt of a bond's cash flows, where the weights are the present values of each cash flow as a proportion of total bond price.
Calculate PV of each coupon and face value, multiply by year, divide by price.
Result: Duration = 5.97 years
Duration is also the price sensitivity measure — a 1% rise in yields causes roughly a Duration% fall in price (Modified Duration).
Duration Properties
| Property | Effect on Duration |
|---|---|
| Zero coupon bond | Duration = Maturity (all cash flow at end) |
| Higher coupon rate | Shorter duration (more weight on earlier payments) |
| Higher YTM | Shorter duration (future flows discounted more heavily) |
| Longer maturity | Longer duration (but less than proportionally) |
| Perpetuity | Duration = (1 + y) / y |
Duration Immunization Strategies
Strategy 1: Target Date Immunization
- Goal: Ensure a specific sum is available at a target date, regardless of interest rate changes
- Method: Match the bond's duration to the investor's holding period (not maturity)
- Works because: Price risk and reinvestment risk offset each other when duration = horizon
Strategy 2: Net Worth Immunization
- Goal: Protect the surplus (assets − liabilities) against rate changes
- Method: Set asset portfolio duration = liability duration
- Used by: Insurance companies, pension funds
- If asset duration = liability duration, any rate change affects both sides equally → surplus preserved
Dividend Discount Model (DDM)
DDM Framework
The intrinsic value of a stock equals the present value of all future dividends, discounted at the investor's required return (cost of equity, ke).
Gordon Growth Model (Constant Growth DDM)
When dividends grow at a constant rate g forever, the infinite sum collapses to the growing perpetuity formula.
Multi-Stage DDM
Real companies often have a high-growth phase followed by stable long-run growth. Value each period separately, then apply Gordon Growth for the terminal value.
Worked Example: Multi-Stage
Given: D_0 = $2.00, ke = 15%, g1 = 10% for 2 years, then g2 = 5% forever
DDM Sensitivity
The Gordon Growth formula is highly sensitive to assumptions. Small changes in ke or g have a large impact on valuation.
Formula Reference — Session 2
Complete Formula Sheet
Six Rules — Quick Reference
| # | Rule | Direction |
|---|---|---|
| 1 | Yield ↑ → Price ↓ (Inverse relationship) | Always |
| 2 | Longer maturity → Greater price sensitivity | Always |
| 3 | Sensitivity increases at a decreasing rate as maturity lengthens | Always |
| 4 | Lower coupon → Greater price sensitivity | Always |
| 5 | Price gain from yield fall > Price loss from equivalent yield rise (convexity) | Benefit to holders |
| 6 | Lower initial yield → Greater sensitivity to a given change | Always |