The Duration Trap

For most of the past 40 years, bond investors had one reliable experience: when things got scary, bond prices went up. Stocks fell, investors fled to Treasuries, yields dropped, and the bond allocation in a balanced portfolio did exactly what it was supposed to do — absorb the shock.

That pattern broke in 2022. It is breaking again now. In the three weeks since February 27, the 10-year U.S. Treasury yield has risen 45 basis points to 4.39%. The 30-year yield has risen 33 basis points to 4.96%. This is not bonds acting as a safe haven. This is bonds falling alongside equities — the exact scenario that balanced portfolio theory says should not happen.

The reason is the same as 2022: inflation. When the threat is deflation or recession, the Fed can cut rates, bonds rally, and the hedge works. When the threat is inflation — sticky, supply-driven, geopolitically amplified inflation — the Fed is trapped. It cannot cut. Yields rise. And bonds become part of the problem, not the solution.

Duration is the single most important number in bond investing, and almost no retail investor knows theirs.

In simple terms, duration measures how sensitive your bond or bond fund is to interest rate changes. A bond fund with a duration of 7 years — like the iShares 7-10 Year Treasury ETF (IEF) — will lose approximately 7% in value for every 1% rise in interest rates. That is not a small number. It means the "safe" part of your portfolio can lose more than many equity positions in a rate shock.

The problem is labeling. Bond funds marketed as "intermediate-term" or "core" often carry durations of 5-8 years. The word "core" sounds conservative. A duration of 7 sounds abstract. But -7% on a rate move is very concrete, and it has happened repeatedly in the current cycle.

Consider what happened in 2022: the Fed raised rates from near-zero to 5.25%. The Bloomberg U.S. Aggregate Bond Index lost 13%. TLT, the popular 20+ year Treasury ETF, lost 31%. These were not speculative instruments. They were the most commonly held "safe" assets in retail portfolios. The duration trap is not a theoretical risk — it is a realized loss that millions of investors experienced and many still have not fully recovered from.