A loan with moving prices.
or, what 2022 actually taught us about the safe asset
Coupon, price, yield
When a bond is issued, it pays a fixed , say 4% on a $1,000 bond, $40 a year, every year, until it matures. After that, the bond trades on a secondary market. If interest rates rise, brand-new bonds offer a better deal, so the price of the old 4% bond falls until its matches the new normal. The doesn't change; the price does. That price move is what shows up in your fund's NAV.
What duration really is
measures how much a bond's price moves when rates move. Rule of thumb: a bond with duration 10 loses about 10% of its price if interest rates rise 1 percentage point, and gains about 10% if they fall 1 point. A 2-year bond has a duration around 2; a 30-year bond, around 18. That is why long-dated bond funds dropped 25–30% in 2022 when rates rose ~2%, and why short-dated funds barely flinched.
The shape of rates
If you plot bond against their maturity (3 months, 2 years, 10 years, 30 years), you get the . Normally it slopes up: longer maturity, more yield to compensate for the wait. When the curve inverts, short rates above long rates, the market is saying 'we expect cuts, because something will break'. Every US recession since the 1960s was preceded by a curve inversion, though the lag is unreliable.
Normal
Long yields above short. The default. The market is calm, expects steady growth, and you get paid extra for tying money up.
Flat
Short and long pay roughly the same. The market is undecided. Often a transition phase between normal and inverted.
Inverted
Short yields above long. The market expects rate cuts, usually because something is breaking. Every US recession since the 1960s was preceded by an inversion.
Match the duration to your horizon.
are not the safe asset. They are the predictable asset, *if* the duration matches the time you can wait. A 30-year bond is a 30-year commitment; held to maturity, you get every and your money back, but along the way the price will whip around. Most beginner portfolios are best served by short-to-intermediate duration funds (2–7 years) where price swings are small and the yield is real.