How Debt Mutual Funds Work

Why can a debt fund go down?

Lakshmi moved a large part of her retirement corpus into debt funds when she stopped working, on the entirely sensible reasoning that she could no longer afford the swings of an equity portfolio. She was told these were the conservative option, and they are.

Then she opened her statement and the value had fallen. Not by much, but it had fallen, which was the one thing she understood this money was not supposed to do. Nobody had defaulted, nothing had gone wrong, and no one had warned her it could happen at all.

What she had not been told is what a debt fund actually is. It pools money from many investors and lends it out, buying bonds, government securities, commercial paper and similar instruments, and she owns a share of that portfolio. Two things follow from that, and between them they explain nearly everything that confuses people about this asset class.

She owns the portfolio's value rather than a promise. Nobody owes her a return. A fixed deposit is a bank's contractual obligation to pay her a stated amount on a stated date; a debt fund is a share of a pool of assets whose worth changes. And that worth is recalculated every day, with the holdings marked to whatever they would fetch and a per-unit value published. So a change in market conditions appears in her account immediately, rather than being invisible the way it is inside a deposit.

That daily valuation is the whole source of her surprise. The fund fell on a day when nothing had gone wrong at all, simply because interest rates had moved.

Where do debt fund returns come from?

Three sources, and separating them matters because they behave quite differently.

Most of the return in normal conditions is interest received from the holdings, which is steady and reasonably predictable. On top of that sit price changes as rates move: when rates fall the holdings gain value, when rates rise they lose it, and the longer the fund lends for the larger that component becomes. This is the volatile part, and it is what moved Lakshmi's statement.

The third source is credit events, and it runs almost entirely in one direction. A downgrade or a default reduces value, and there is no equivalent windfall on the upside beyond the interest that was already being collected.

A fund's headline past return blends all three, which is why it tells you so little about what happens next. A period of falling rates flatters every debt fund regardless of how it was managed, and a quiet stretch flatters the funds taking credit risk, because the risk they took has not yet been called in.

What defines the risk of a debt fund?

Every debt fund is a position on two dials, and once you know both you know most of what matters.

The first is how long it lends for, measured by duration. Longer lending pays more yield and moves more in price when rates change — a fund holding very short paper barely reacts, while a long-duration or gilt fund can move sharply. The second is who it lends to, measured by credit quality. Lending to the government carries no default risk in rupees; lending to weaker corporate borrowers pays more and can lose money permanently.

These two are independent, which is the part that catches people. A fund can be short duration and poor credit, or long duration and impeccable credit, and categories with reassuring names exist at several points on both dials. That is why the name on the fund is a weak guide and the factsheet is a strong one.

Is a debt fund the same as safe?

The phrase does real damage, because it invites the comparison Lakshmi made — against a bank deposit — and the two are structurally different products.

A deposit has a contractual return, no daily valuation and no market price. A debt fund has none of those things. It can fall in value. It can be affected by what other investors do, since large redemptions force selling. And in a stressed market it can restrict redemptions or segregate an impaired holding, leaving part of the money frozen until recovery.

None of this makes debt funds a bad choice, and for Lakshmi they may well be the right one. They offer daily liquidity in normal conditions, professional diversification across many borrowers, and generally better tax treatment on longer holdings than interest income receives. But they are investments, and the sentence "it's a debt fund, so it's safe" is the belief that precedes most unhappy outcomes here.

How do you read a debt fund properly?

Ignore the name and ignore the past twelve months' return. Four things carry the information.

Duration tells you how much it will move when rates change — roughly its value in per cent for each percentage point — so match it against how long the money can be left alone. Credit quality of the actual holdings, not the average rating, tells you where the lowest-rated money sits and how much of it there is. Concentration matters separately, because a large single exposure to a weak borrower is a different proposition from the same total spread thinly across many.

And the yield relative to peers is the summary of all of it: if a fund is paying more, something is being taken — longer duration, weaker credit, or less liquid paper — and it is worth knowing which, because you are being paid for it.

To those four add the expense ratio, which matters more here than anywhere else. In an asset class where the entire return may be a few per cent, the annual charge consumes a far larger share of it than the same charge would in an equity fund.

How does the purpose of the money shape the choice?

The most reliable starting point is what the money is there for rather than the fund categories, because the same dial position produces very different outcomes depending on the job.

Money that might be needed within weeks, or an emergency fund, requires above all else the ability to reach the full amount on an unpredictable day. Overnight and liquid categories, with the shortest duration and the highest credit quality, supply that in normal conditions. The low yield is the price of the property actually needed — not a deficiency to be optimised away.

Money with a year or two until it is needed can tolerate some price movement, because a rate-driven fall with time to wait is temporary rather than realised. Short-duration funds of good credit quality work within that tolerance. Duration and credit quality are independent: duration limits how far rates can move the value; credit quality determines whether the value recovers at all.

Money serving as stable ballast in a long-term portfolio can carry longer duration. But credit quality should stay high regardless, because the purpose of that ballast is to behave differently from equities during a crisis — and weak corporate credit tends to fall at precisely the same time equities do, which defeats the point. A fund carrying long duration and weak credit is exposed on both dials at once.

The appetite for higher return inside a fixed-income allocation runs into a structural limit: credit risk is capped at the interest the borrower promised, while equity's upside is not. The trade has a different shape from equity exposure and a different downside.

For Lakshmi, identifying which job each slice of the corpus is doing — and keeping credit quality high throughout — preserves the reason for holding fixed income separately from equities.

How are debt fund gains taxed?

The tax treatment of debt fund gains in India has changed in recent years, and it differs from the treatment of bank interest in ways that can decide which of two similar options is better after tax.

This page does not state the current rules, because they change and a confidently stated out-of-date rate is worse than none at all. Check the current treatment against a primary source, or with somebody qualified, before choosing between a deposit and a debt fund on tax grounds — and be particularly careful with older articles and sales material, which frequently describe a regime that no longer applies.

What to take away

A debt fund is a share of a portfolio of loans, valued daily. You own the value of those loans rather than a promise, which is why the price moves and why it is not a deposit.

Judge it on two dials — how long it lends for, and to whom — plus concentration and cost. Match the duration to how long the money is committed, keep credit risk out of anything whose job is safety, and check the current tax treatment rather than trusting anything written more than a year ago. Lakshmi's statement was not a malfunction; it was the product doing exactly what it does, in a way nobody had explained to her.