Price/yield see-saw
A 1% yield move has a bigger price impact on long, low-coupon bonds than on short, high-coupon ones—duration in action.
Assumption: clean price (no accrued interest). Coupon dates are simplified; for professional use, verify day-count and accrual conventions.
| Period | Cash Flow | Discount Factor | Present Value | Cumulative PV |
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Summary (voice-friendly): A bond’s price is the present value of all future coupons plus the face value, discounted by the yield per period. YTM is the annualized rate that makes those discounted cash flows equal today’s price.
A bond is a loan to a borrower (issuer). The investor receives periodic interest payments (coupons) and the face value at maturity. Prices move inversely with yields: when yields rise, present values fall, so prices drop (and vice versa).
Clean price excludes accrued interest; dirty price adds accrued interest between coupon dates. This tool uses clean price. For settlement-day accuracy, add accrued interest based on the chosen day-count convention (e.g., 30/360, Actual/Actual).
\( P = \sum_{t=1}^{n} \frac{C}{(1 + r_p)^t} + \frac{F}{(1 + r_p)^n} \), where \( C \) = coupon per period, \( F \) = face value, \( r_p = y/f \), \( n = f \cdot T \) periods.
Face \( F = \$1{,}000 \), coupon rate \( 5\% \) (so \( C = \$50 \) per year), semi-annual coupons (\( f=2 \Rightarrow C/f = \$25 \) per period), maturity \( T = 10 \) years (\( n = 20 \) periods), YTM \( y = 6\% \Rightarrow r_p = 0.06/2 = 0.03 \).
Coupon PV \( = 25 \times \frac{1 - (1+0.03)^{-20}}{0.03} \approx \$372.45 \).
Face PV \( = 1000 \times (1+0.03)^{-20} \approx \$553.68 \).
Price \( P \approx \$926.13 \) (discount bond since YTM > coupon rate).
Higher yields increase the discount rate, which lowers the present value of future cash flows—so price falls.
YTM equals the internal rate of return if you hold to maturity and reinvest coupons at the same yield. Realized return may differ if you sell early or reinvest at different rates.
Longer maturities and lower coupons generally increase duration (more rate sensitivity). Higher coupons and shorter maturities reduce it.
Note: This page simplifies calendars and accrual. Professional workflows may require day-count conventions, holiday calendars, settlement lags, and callable/putable features.
A 1% yield move has a bigger price impact on long, low-coupon bonds than on short, high-coupon ones—duration in action.
Quotes are usually “clean” (no accrued interest). The cash you pay is “dirty”: clean price + accrued coupon since last pay date.
Zeros have the highest duration for a given maturity because every pound comes at the end—great hedge, big rate sensitivity.
YTM assumes reinvesting coupons at the same yield. If reinvestment rates drop, realized return can lag even if held to maturity.
Positive convexity means price falls less than duration predicts on a rate rise and rises more on a rate drop—nice asymmetry.