Market risk, or “principal risk” is the chance that a downturn (or a bad investment) chews up your money. It’s there for both stocks and bonds — when interest rates rise, bondholders will see the market value of their paper shrink — and for most people it’s the big bugaboo.

Inflation or purchasing-power risk for most people is the “risk of avoiding risk” — the opposite end of the spectrum from market risk — the possibility that you are too conservative and your money can’t grow fast enough to keep pace with inflation