Choosing a bond ETF: credit quality, duration and inflation-linked (advanced)
"A bond fund" is not one thing — credit quality, duration and inflation-linkage each move independently, and a fund can be conservative on one axis and aggressive on another at the same time.
Three separate questions, one bond fund
Treating "bond fund" as one undifferentiated bucket is the single most common way a bond screen goes wrong. A fund is really answering three separate, independent questions at once: how likely are the borrowers to pay you back ( Whether the bonds inside are higher-rated (“Investment Grade”), lower-rated and higher-yielding (“High Yield”), or “Not Rated” because we found no clear signal. More → ), how much does the price swing when interest rates move ( How sensitive the bond fund’s price is to interest-rate changes, from Ultra-short (barely moves) to Long (moves the most) — shorter tends to wobble less when rates shift. More → ), and do the payouts keep pace with inflation or stay fixed regardless of it ( Whether the bonds’ payouts move with inflation (“linkers”/TIPS) or pay a fixed amount regardless of inflation (“nominal” bonds). More → or not). A fund can be conservative on one axis and aggressive on another — a long-duration Investment Grade fund is a genuinely different bet from a short-duration one, even though both are "Investment Grade".
Credit quality: how it's actually worked out here
To be straight about the method: our credit-quality band comes from the fund’s name and the index it tracks, not a rating agency’s fund-level opinion or a holding-by-holding read of every bond inside. "Not Rated" means we found no clear signal from that — it doesn’t mean the underlying bonds carry no credit rating at all. Investment Grade bonds are generally steadier but pay less; High Yield pays more to compensate for a real, higher chance a borrower struggles to pay. Screening on this filter is soft by design: a fund we can’t classify stays in your results rather than being hidden, with a coverage note on what share of funds the band actually covers.
Duration: the dial that matters most day-to-day
Of the three, duration is the one that moves a bond fund’s price most visibly in the short run — it’s the same mechanism the beginner guide on bonds covers for a single bond’s price and rates, just applied across a whole fund’s holdings. A short-duration fund barely reacts to a rate move; a long-duration one swings much further, in either direction. Neither is "better" — shorter typically pays a lower yield in exchange for calmer rate-sensitivity; longer typically pays more but tests your nerve more when rates move against you. Matching duration to how soon you might need the money, or how much rate-driven wobble you can tolerate, is the actual decision this filter is for.
Inflation-linked: a structural fact, not a forecast
This one is different in kind from the other two: it’s a fixed structural fact about the bond, not a risk gradient. An inflation-linked bond adjusts its interest and/or principal as prices rise, so it’s built to hold its real, after-inflation value; a nominal bond pays exactly what it promised on day one, and inflation quietly erodes what that’s worth over time. Choosing inflation-linked exposure isn’t a bet that inflation will rise from here — it’s a decision about which kind of promise you’d rather hold, independent of your view on where inflation actually goes next.
Combining the three for a real selection
Put together, the three dials answer a genuinely specific question: "a fund that’s mostly Investment Grade, short-duration, and nominal" describes a conservative, rate-insensitive holding built for capital stability over the next few years — a different animal from "High Yield, long-duration, inflation-linked", which is a much more volatile bet stacked on three separate risk premia at once. Screening bond funds one filter at a time and stopping at the first match misses that the combination, not any single dial, is what actually defines the fund’s behaviour.