ETF vs mutual fund: what actually differs

The difference starts with when your order gets a price.

A mutual fund does not trade on a market at all. You send the fund an order, and it fills at the next net asset value struck after the cut-off: everything the fund holds, minus what it owes, divided by the shares outstanding. That valuation point falls after the close in the United States and often earlier in the day elsewhere, but the mechanism is the same wherever the fund is domiciled. Everyone dealing on a given valuation gets the same number, and nobody knows what it is at the moment they commit. Pricing forward like that is the point of it: it stops anyone buying or selling on a value that is already known to be stale.

An ETF holds a portfolio in the same way, but its shares change hands between investors on an exchange, so a price is quoted continuously through the session. You can see it before you buy, refuse anything worse with a limit order, and be filled in seconds.

That reads as a straight advantage until you ask what it is worth. Choosing the minute inside a single session matters to someone trading and does nothing at all for someone holding for twenty years. What it adds is a decision, and with it a way to get a poor price, which the once-a-day mechanism removes by design.

So the consequence runs both ways. The all-day price makes an ETF easier to trade, and easier to trade badly.

Behind an ETF's exchange price sits a mechanism a mutual fund has no everyday equivalent for. Large dealers, known as authorised participants, can create new ETF shares by delivering the fund a basket of the underlying holdings, or redeem shares by handing a block back and taking a basket. They do it when the market price drifts far enough from the value of the holdings to be worth their own costs, which is what pulls the two together, and also why a small premium or discount can sit there untouched.

The part that reaches an ordinary investor is what happens on the way out. A mutual fund usually meets redemptions in cash, so persistent net selling can force it to sell holdings, and the gains that realises belong to everyone who still owns the fund. Under United States rules a fund has to distribute its realised net gains to keep its pass-through tax treatment, which is why a shareholder can owe capital gains tax in a year the fund lost money and they sold nothing.

An ETF settles most of those redemptions in securities instead. Delivering shares is not a sale, so far less gain is realised, and most broad index ETFs pass out little beyond dividends.

Three things narrow that advantage, and a fair comparison states all three. It is a taxable account effect: inside a tax-advantaged account, distributions are not taxed as they arrive and the gap all but closes. It is a United States effect: where a fund is not obliged to distribute realised gains and the investor is instead taxed on sale, there is much less for in-kind redemption to save. And what must be distributed is net gains, so a low-turnover index mutual fund, or one still carrying losses forward from an earlier fall, can distribute close to nothing for years while an active fund in the same wrapper distributes a great deal.

The gap is therefore widest where turnover is high or the fund is shrinking, and narrowest between two broad index funds tracking the same thing.

Both wrappers quote an expense ratio, and on neither one is it the whole cost. It is also less standard than it looks: what has to be counted inside that percentage differs between jurisdictions and between documents, and dealing costs sit outside it almost everywhere.

For an ETF the visible addition is the bid-ask spread, paid on the way in and again on the way out. On a heavily traded broad index fund it is often a basis point or two, small enough to ignore. On a narrow or thinly traded one it can reach a full percentage point, which swallows a fee saving many times over for someone buying every month. Spreads widen at the open, near the close and in falling markets, which is exactly when the most people want to deal. Treat any figure quoted here as a snapshot: the spread on your screen at the moment you deal is the one that applies to you.

The premium or discount to the value of the holdings gets called a second cost, and that needs care, because you buy at one and sell at another. What you pay is the change between the two, not the level of either. Bought and sold at the same half-percent premium, it costs nothing on that account. The damage comes when a premium at purchase has turned into a discount at sale, which is likeliest in a stressed market or a thin fund.

A mutual fund has no quoted spread in most markets, and that is not the same as having no dealing cost. The fund pays commissions and crosses spreads itself whenever flows force it to trade, and that comes out of the portfolio you own alongside everyone else. Some markets make the charge explicit instead: a dual-priced fund quotes a buying price and a selling price, and a swing-priced one moves the whole valuation toward whichever side is dealing, so the cost lands on the people causing it. The share class can add its own charges on top: a sales load, a fee for redeeming quickly, or a distribution charge folded into a higher yearly figure for the same portfolio.

Neither list settles it alone. Frequency decides which one bites, because dealing costs scale with how often you trade and fees scale with how long you hold.

For a broad index sold in both wrappers, the choice is close, and three things decide it.

The account comes first. In a taxable account under United States rules, in-kind redemption is a real edge for the ETF, because a mutual fund can hand you a bill you did not schedule. Inside a tax-advantaged account that edge has nothing to work on, and what is left is the fee, how closely each one tracks, and whether you would rather cross a spread at the moment you deal. Where the tax code charges you on sale rather than on what the fund distributes, the edge is smaller again before any account wrapper is applied.

How you invest comes second. Paying a fixed amount in on a schedule, which is dollar-cost averaging, suits a mutual fund, since it buys an exact amount in fractions of a share as a matter of course. An ETF does the same only where the broker supports recurring fractional buys, and it crosses a spread each time.

What is on the menu comes third, and it often settles the question before you ask it. Some strategies exist in one wrapper only, and workplace retirement plans in the United States commonly list mutual funds and nothing else.

Minimums matter mainly at the outset: one share, or a fraction of one, against whatever the fund sets. Entry points have come down a long way across the industry, so read the fund's current document rather than a figure you remember.

The wrapper is the smaller decision in any case. What sits inside it, whether an index fund or an active one, and what that charges, move the outcome further than this choice does.