ETF liquidity is your ability to buy or sell the required quantity at a reasonable cost. The number of units traded on screen is only part of that assessment. The underlying assets, market makers, available quotes and your order size also matter.
Australia's growing ETF market makes this a useful check before placing an order. Betashares' August industry review, published on 16 September 2026, reported A$7 billion in monthly net inflows and total industry assets of A$382 billion. Industry growth does not mean every ETF offers the same execution conditions.
Two sources of ETF liquidity
You normally buy ETF units from another participant on the exchange. Behind that secondary market, authorised participants can create or redeem units with the fund under its terms.
This process links the traded unit to the underlying portfolio. Market makers can use the underlying assets and hedges to support quotes, rather than relying only on another retail investor wanting the opposite trade at that moment.
The ASX explanation of ETP market-making arrangements describes how market makers estimate portfolio value and quote buy and sell prices.
The mechanism helps explain why a low-volume ETF can still offer a usable quote. It does not guarantee narrow spreads or unlimited size, especially during stressed markets.
Read the bid and offer separately
The bid is the available buying price at which you could sell. The offer, or ask, is the available selling price at which you could buy, subject to the displayed quantity.
Suppose the market is:
| Quote | Price |
|---|---|
| Bid | $24.98 |
| Offer | $25.02 |
| Midpoint | $25.00 |
| Full spread | $0.04 |
The full spread as a percentage of the midpoint is:
$0.04 ÷ $25.00 × 100 = 0.16%, or 16 basis points.
Buying 1,000 units at $25.02 costs $25,020 before fees. Selling those units immediately at an unchanged $24.98 bid returns $24,980: a $40 difference.
That is a hypothetical immediate round trip. The purchase alone is $20 above the midpoint; calling the full $40 spread the one-way midpoint cost would double it.
NAV and the trade price answer different questions
Net asset value per unit, or NAV, is the value of fund assets less liabilities, divided by units. Its usefulness depends on the valuation time and methodology.
An indicative intraday value, often called iNAV, estimates value during the session where available. It can still be stale or rely on markets that are closed.
A simple premium calculation is:
Premium or discount = (market price ÷ relevant NAV − 1) × 100
If a current, appropriate NAV estimate is $25.00 and the offer is $25.10, the offer is 0.40% above that estimate. This does not by itself prove an arbitrage opportunity. Check the time, currencies, underlying market and costs needed to realise that value.
An old NAV and a fresh quote can differ for legitimate reasons. Comparing them without adjusting the timestamp may label a normal market move as a premium.
The underlying market's hours matter
An ASX ETF holding US shares may trade while the main US equity session is closed. Market makers can use futures, currencies and other information, but pricing and hedging conditions differ from an overlapping session.
Look for a change in the spread or quoted size when the underlying market is unavailable, during a local auction, or around a major announcement. Do not apply one universal “best minute” to every ETF.
Betashares' spread explainer discusses timing and underlying-market considerations. The ASX hours guide helps distinguish continuous trading from auction periods.
Match the order to the quantity
A quote for 200 units does not establish the execution price for 20,000 units. A large market order may consume several price levels.
A limit order sets a price boundary; it does not promise a fill. Watch for partial fills and the remaining order's expiry. If your order is material relative to displayed depth, ask the broker about its process before submitting.
Compare the total cost of the planned trade, including brokerage and currency charges where relevant. The breakeven-cost guide shows how small costs can matter relative to planned risk.
A five-minute ETF execution check
Before confirming an order:
- Verify the exact fund, exchange and exposure.
- Check the current bid, offer and available quantity.
- Calculate the spread relative to the midpoint.
- Check the timestamp of any NAV or indicative value.
- Identify whether the underlying markets are open.
- Choose the limit, quantity and expiry deliberately.
- Reconcile the execution confirmation, including partial fills and fees.
Save the quoted spread and your reason for selecting that session. In a later review, compare execution with the information available at the time, not a better quote that appeared hours afterwards.
Keep execution separate from portfolio fit
An ETF can be easy to trade and still duplicate holdings you already own. Use the ETF overlap guide for that separate decision.
Likewise, a well-executed purchase can lose money when the underlying assets fall. In your Swingfolio record, distinguish the investment thesis from the execution decision so a review can assess both.
Common questions
Does low daily volume mean I cannot sell?
Not necessarily. Inspect live depth, market-maker quotes and the underlying assets. Your required size and market conditions still matter.
Does a market maker guarantee my price?
No. Quotes and size can change. Read the order confirmation and fund risks rather than assuming a permanent spread.
Is the last traded price a reliable purchase price?
It records a past execution. Use the current offer and available quantity to assess a potential buy.
Reviewed 27 September 2026. Worked quotes are hypothetical. General information only.