Should I put my nest egg in a 30-year Treasury bond?

A 30-year Treasury bond is often framed as the ultimate "safe" retirement holding: it carries the full faith and credit of the U.S. government, so the risk of outright default is negligible. But safety of principal is not the same as safety of outcome. The real risk in a long-duration bond is what happens to its price when interest rates move.

Because a 30-year bond locks in a fixed coupon for three decades, its market value swings sharply as prevailing yields change. If rates rise after purchase, the bond's price falls — and an investor who needs to sell early can lock in a loss. If rates fall, the bond gains value, but reinvestment of future coupons may occur at lower yields. Inflation adds a quieter risk: a fixed payment stream can lose purchasing power over 30 years.

What to watch: the direction of long-term yields and inflation expectations. These determine whether a long bond's guaranteed income actually preserves a nest egg's real value.