Guide

Yield to maturity explained

Two corporate bonds both advertise a 5% coupon. One trades at $980; the other at $1,040. Which is the better buy? The coupon rate alone cannot answer that — you need yield to maturity (YTM), the annualized internal rate of return you earn if you purchase the bond at today’s price, collect every coupon payment, and receive face value at maturity. YTM folds together the coupon stream, purchase price, and time to maturity into a single comparable number. Bond desks, fund managers, and retail investors use it to rank alternatives on equal footing. This guide defines YTM, contrasts it with current yield and yield to call, walks through the price-yield relationship for premium and discount bonds, shows how YTM is calculated, presents a Harbor Capital bond-sleeve worked example, offers a metric decision table, common pitfalls, and an investor checklist alongside our bond fundamentals guide, duration and rate-risk primer, and yield curve explainer.

What yield to maturity measures

Yield to maturity is the discount rate that equates the present value of a bond’s future cash flows — semiannual coupon payments plus principal repayment at maturity — to its current market price. Mathematically, YTM is the bond’s internal rate of return (IRR) under two assumptions: you reinvest every coupon at the same YTM until maturity, and the issuer does not default or call the bond early.

YTM is always quoted as an annual percentage. For U.S. Treasuries and most corporates, coupons pay semiannually, so the solver works on a 6-month period basis and annualizes the result. A bond with a 4% coupon paying $20 every six months on a $1,000 face value has a coupon rate of 4%, but its YTM depends entirely on what you pay today.

The core intuition

If you buy below par (a discount bond), you earn coupons plus a capital gain when principal is repaid at $1,000 — so YTM exceeds the coupon rate. If you buy above par (a premium bond), coupons are partly offset by a capital loss at maturity — YTM falls below the coupon rate. At par, YTM equals the coupon rate (ignoring accrued interest timing).

Current yield vs YTM vs yield to call

Investors encounter several yield metrics. Using the wrong one leads to bad comparisons — especially on callable bonds and premium issues.

Metric	Formula (simplified)	What it captures	When it misleads
Coupon rate	Annual coupon / face value	Contractual payment at issuance	Ignores market price entirely
Current yield	Annual coupon / market price	Income relative to price today	Ignores capital gain/loss at maturity
Yield to maturity	IRR of all cash flows to maturity	Total return if held to maturity	Assumes no early call; reinvestment at YTM
Yield to call (YTC)	IRR to first call date at call price	Return if issuer calls early	Call may never happen
Yield to worst (YTW)	Lowest of YTM, YTC, put yields	Conservative callable-bond yield	Still a model, not a guarantee

Current yield is a quick income snapshot: a $1,000 face bond with a $50 annual coupon trading at $900 shows a 5.56% current yield. But YTM also accounts for the $100 gain at maturity, pushing total return higher. On premium bonds the opposite happens — current yield overstates true return because you lose principal. For any hold-to-maturity decision, YTM (or YTW for callables) is the right headline number.

How YTM is calculated

The bond pricing equation sets price equal to the present value of cash flows, solved for the discount rate y (YTM):

Price = Σ [ C / (1 + y/2)^t ] + Face / (1 + y/2)^(2n)

where C is the semiannual coupon, n is years to maturity, and t runs over each payment period. There is no closed-form algebraic solution for y when maturity exceeds one period — financial calculators, spreadsheet YIELD() functions, and Bloomberg terminals use iterative root-finding (Newton-Raphson) to converge on YTM.

Approximation for quick estimates

A common shortcut for annual-coupon bonds near par:

YTM ≈ [ C + (Face − Price) / n ] / [ (Face + Price) / 2 ]

Example: 5% coupon ($50), 10 years left, price $950: YTM ≈ [50 + (1000 − 950) / 10] / [(1000 + 950) / 2] = 55 / 975 ≈ 5.64%. Exact YTM is about 5.65% — close enough for screening, but use a proper solver for trading decisions.

Accrued interest

Bonds trade on a clean price (quoted without accrued interest) plus accrued interest paid to the seller. YTM is computed on the dirty price (clean + accrued). Retail platforms usually display YTM on the all-in cost you actually pay.

Price, yield, and the inverse relationship

Bond prices and yields move in opposite directions. When market interest rates rise, existing bonds with lower coupons must drop in price until their YTM matches the new market level. The sensitivity of that price change is measured by duration — longer maturity and lower coupon mean larger price swings for a given yield change.

Plotting YTM against maturity for bonds of the same credit quality produces the yield curve. A normal upward-sloping curve means longer maturities offer higher YTM — compensation for locking up money longer. An inverted curve (short rates above long rates) often signals recession expectations and complicates ladder construction.

Credit spreads add a layer

YTM on a corporate bond embeds a default-risk premium over Treasuries of the same maturity — the credit spread. Two bonds with identical coupon and maturity can have very different YTMs if one issuer is rated BBB and another AA. Always compare YTM within the same credit tier, or strip out the Treasury benchmark to isolate spread.

Worked example: Harbor Capital intermediate bond sleeve

Harbor Capital’s fixed-income desk screens two 2031-maturity investment-grade corporates for a $500,000 sleeve. Both have $1,000 face value and pay semiannual coupons.

Bond	Coupon	Price	Current yield	YTM	Duration
Harbor Utilities 4.25s 2031	4.25%	$968	4.39%	4.62%	6.1 yr
Harbor Logistics 5.00s 2031	5.00%	$1,028	4.86%	4.58%	5.8 yr

A naive investor picks Harbor Logistics for the higher coupon and current yield. The allocator correctly ranks by YTM: Harbor Utilities offers 4 bps more total return to maturity despite a lower coupon, because the discount price amplifies return through the pull-to-par effect. After checking that both issuers are A-rated with stable OAS spreads inside sector medians, the desk sizes Utilities at 60% of the sleeve and Logistics at 40%, keeping portfolio duration near 6.0 years — aligned with their liability horizon.

If Harbor Logistics were callable in 2028 at $1,020, the desk would compute yield to call (likely ~4.35%) and yield to worst (min of YTM and YTC). The premium price makes early call likely if rates fall — YTW becomes the binding metric, and Utilities looks even more attractive on a risk-adjusted basis.

Metric decision table

Your question	Use this metric	Why
Which bond earns more if I hold to maturity?	YTM	Captures coupons plus capital gain/loss
How much income does this pay right now?	Current yield	Simple coupon / price snapshot
Callable corporate — worst-case return?	Yield to worst	Conservative across call and maturity paths
How much rate risk am I taking?	Duration + convexity	Price sensitivity, not a return measure
Taxable vs muni bond comparison	Taxable-equivalent yield	Adjusts muni YTM for investor tax bracket
Fund holdings — blended exposure?	SEC yield / distribution yield	Fund-specific rolling income measures

Common pitfalls

Comparing coupon rates instead of YTM — premium bonds look generous on coupon but may underperform discount peers on total return.
Ignoring call risk on premium bonds — issuers call when it saves them money; YTM assumes maturity, which may never arrive.
Reinvestment-rate assumption — YTM assumes coupons reinvest at YTM; in falling-rate environments realized return can exceed YTM; in rising rates it can fall short.
Confusing YTM with expected return on bond funds — funds have no fixed maturity; NAV fluctuates daily. Use SEC yield and total return history instead.
Pre-tax vs after-tax YTM — munis and Treasuries have different tax treatment; compare on a taxable-equivalent basis.
Bid-ask spread on retail lots — quoted YTM may use mid price; small investors pay the ask, lowering realized yield.
Default risk not in the formula — YTM is a promised return, not a probability-weighted expectation. High-yield YTM can mask credit losses.

Investor checklist

Rank individual bonds by YTM (or YTW if callable), not coupon rate or current yield alone.
Confirm clean vs dirty price and accrued interest before comparing platforms.
Check call schedule and compute yield to worst on any premium callable.
Match credit quality before comparing YTM across issuers.
Pair YTM with duration to understand rate-risk trade-offs.
Adjust muni YTM for your marginal tax rate when comparing to taxable bonds.
Remember reinvestment assumption — stress-test with lower reinvestment rates if rates are falling.
For bond funds, use SEC yield and rolling total return — not a single bond’s YTM.
Factor bid-ask spread into small-lot purchases.
Revisit YTM after large rate moves — stale quotes misprice ladders.

Key takeaways

Yield to maturity is the IRR of holding a bond to maturity — the standard total-return yardstick.
Current yield ignores capital gain or loss at maturity; use YTM for hold-to-maturity decisions.
Discount bonds have YTM above coupon rate; premium bonds have YTM below coupon rate.
On callable bonds, yield to worst is the conservative comparison metric.
YTM embeds credit spread and rate risk — always compare within the same quality and horizon context.