Bond Pricing

A bond's price is the present value of all its future cash flows:

Price = Σ [Coupon / (1+YTM)^t] + [Face Value / (1+YTM)^n]

For a semi-annual bond: use semi-annual coupon = Annual Coupon / 2, and semi-annual YTM = YTM / 2, and n = years × 2.

Example: 5% annual coupon, 3-year bond, face value ₹1,000, YTM = 6%:

  • Year 1: 50 / 1.06 = 47.17
  • Year 2: 50 / 1.06² = 44.50
  • Year 3: 50 / 1.06³ = 41.98 + 1000/1.06³ = 839.62
  • Price = 47.17 + 44.50 + 41.98 + 839.62 = ₹973.27 (discount bond — coupon < YTM)

Price-Yield Relationship

  • When YTM = Coupon rate: Price = Face Value (par bond)
  • When YTM > Coupon rate: Price < Face Value (discount bond)
  • When YTM < Coupon rate: Price > Face Value (premium bond)

Yield Measures

  • YTM (Yield to Maturity): Discount rate equating PV of cash flows to price. Assumes coupons reinvested at YTM and held to maturity.
  • Yield to Call (YTC): YTM calculated to the call date at call price — relevant for callable bonds in falling rate environments.
  • Current Yield: Annual Coupon / Current Price. Simple but ignores capital gain/loss and reinvestment income.
  • Effective Yield: For bonds with embedded options, uses option-adjusted spread (OAS) instead of YTM.

Duration

Macaulay Duration

The weighted average time (in years) to receive all cash flows, where weights = PV of each cash flow / Total Price.

Zero-coupon bond: Macaulay Duration = Maturity (all cash flow at end)

Coupon bond: Macaulay Duration < Maturity

Modified Duration

Modified Duration = Macaulay Duration / (1 + YTM/m)

where m = compounding periods per year.

Interpretation: If Modified Duration = 5, then a 1% rise in yield → approximately 5% price decline.

% Change in Price ≈ −Modified Duration × ΔYield

Example: Bond with Modified Duration = 7. Yield rises 0.50%: Price change ≈ −7 × 0.005 = −3.5%

Dollar Duration (DV01)

DV01 (Dollar Value of a Basis Point) = Modified Duration × Price × 0.0001

Used in portfolio hedging — tells you $ change in bond value per 1bp yield move.

Convexity

Duration is a linear approximation of price-yield relationship. Convexity captures the curvature.

More accurate price change = (−Modified Duration × ΔY) + (½ × Convexity × ΔY²)

Positive convexity is desirable: for a given yield move, price rises more than duration predicts and falls less. Higher convexity bonds command a premium.

Callable bonds have negative convexity at low yield levels (price is capped by call price even as yields fall).

Credit Analysis

Credit Rating Framework

S&P/FitchMoody'sCategory
AAA, AA, A, BBBAaa, Aa, A, BaaInvestment Grade
BB, BBa, BSpeculative / High Yield
CCC, CC, C, DCaa, Ca, CDistressed / Default

Four Cs of Credit Analysis

  • Capacity: Ability to repay — EBITDA coverage, leverage ratios, free cash flow generation
  • Collateral: Asset quality — liquidation value in default scenario
  • Covenants: Debt covenants protecting bondholders (maintenance covenants, incurrence covenants)
  • Character: Management quality, track record, governance

Credit Spread Analysis

Credit Spread = Bond YTM − Risk-Free Rate (comparable government bond)

Spread reflects: Default risk premium + Liquidity premium

In recessions, spreads widen dramatically (flight to quality). In expansion, spreads narrow.