Episode 40: The See-Saw

Hey! I'd love to hear your thoughts, send me a voice note.Episode Summary Perhaps the most famous rule in fixed income is that bond prices and yields move in opposite directions, always and without exception. Yet, when rates rise and bond portfolios fall, many investors are left bewildered. Why should a perfectly healthy, default-free bond decline in value when every payment is being made on schedule and in full? This episode explains the unyielding arithmetic of the price-yield see-saw, reveals the crucial difference between holding an individual bond to maturity versus holding a rolling bond fund, and details why panic-selling a depressed bond fund is the exact same behavioral trap as selling stocks at the bottom of a crash.Key ConceptsThe Contractual Constraint: The see-saw exists because a bond's coupon is contractually fixed at issue. When market interest rates rise, newly issued bonds offer higher payouts. Because you cannot change your bond's fixed coupon, the only variable that can adjust to make your bond competitive to a buyer is its price.The Price-Yield See-Saw: If you own a 3% bond and market rates rise to 5%, your bond must trade at a discount so that a buyer's total return (coupons plus capital gain to par) equals 5%. If rates fall, the reverse happens: your bond is bid up to a premium.Convexity: The relationship between price and yield is a curve, not a straight line. For conventional bonds, prices rise more when yields fall than they fall when yields rise by the same amount—a structural feature known as convexity.The See-Saw in NumbersConsider a 10-year, $1,000 par value bond with a 3% annual coupon ($30/year) issued at par:At 3% market yield: The bond trades at par ($1,000).If rates rise to 4%: The bond's price falls to $918.89 (down ~8%).If rates rise to 5%: The price falls to $845.57 (down ~15%).Despite no defaults or missed payments, a simple two-percentage-point rise in rates wipes out roughly 15% of the market value of a safe, government-quality bond.Individual Bonds vs. Bond FundsHolding to Maturity: If you hold an individual bond to maturity, the price decline is merely a temporary paper mark-to-market event. The price naturally converges back to par as maturity approaches. However, your opportunity cost is real: you are locked into earning 3% for a decade while 5% is available in the market. You didn't lose principal, but you lost the better alternative.Holding a Bond Fund: A bond fund has no maturity date. It holds a rolling portfolio that is marked to market daily. When rates rise, the fund's net asset value drops immediately. However, as the fund sells maturing bonds and reinvests coupons at the new, higher rates, the increased income eventually compensates for the price drop over a period roughly equal to the fund's duration.The Behavioral TrapJust as in equity markets, the worst thing an investor can do is sell partway down. Panic-selling a bond fund during a rate-hiking cycle converts a temporary paper loss into a permanent capital loss, ensuring you miss out on the higher-yielding reinvestments that serve as your compensation. The only reliable defense is choosing what you will do before the crisis happens.Disclaimer This content is educational and does not constitute financial advice. Speakers are not registered to advise you on securities; please consult a licensed professional for your personal situation.