An ETF can have a low expense ratio and still be expensive to trade. Investors transact at exchange prices, not directly at end-of-day NAV, so bid-ask spread, market depth and the relationship between traded price and indicative portfolio value can matter more than a few basis points of annual fee for short holding periods.
Finin2min summary
Check best bid and ask, not just last traded price.
Using NAV as if it were a guaranteed exchange execution price.
Exchange bid/ask and depth at intended trade time
Rules in practice
| Rule |
|---|
| ETF NAV is the fund's per-unit asset value, while exchange price can trade above or below NAV during the day. |
| Indicative NAV can help price discovery but is not a guaranteed execution price. |
| Bid-ask spread is an immediate trading cost that can dominate TER for small or illiquid ETFs. |
| Limit orders and trading during underlying-market liquidity windows can reduce execution slippage. |
NAV is the per-unit value of the underlying portfolio calculated under the scheme framework; the exchange price is what another market participant is currently willing to pay or accept.
The bid-ask spread is an immediate trading friction: buying at the ask and selling at the bid can create a loss even when the underlying portfolio does not move.
iNAV is an indicative intraday reference, not a guaranteed execution price. Its usefulness depends on timely underlying prices and the ETF’s market-making process.
Thin order books can create larger price impact for market orders. Limit orders help control execution price but can remain unfilled.
International or commodity ETFs can show wider dislocations when the underlying market is closed while the Indian exchange is open.
Tracking error measures divergence of scheme returns from the benchmark over time; trading spread is a separate investor-level execution cost.
For systematic large trades, compare average daily traded value and visible depth around the intended order size, not merely the last traded price.
The spread can cost more than the expense ratio on a short holding period
An ETF investor trades with another market participant on the exchange, so the execution price can sit above or below the underlying portfolio value. NAV is the end-of-day accounting value, while indicative NAV is intended to provide a more frequent reference for the portfolio value during market hours. Neither guarantees that a market order will execute at that level.
Bid-ask spread is an immediate round-trip friction: buying at the ask and selling at the bid can create a loss even if the underlying portfolio has not moved. The effect is especially important for thinly traded ETFs, large orders and stressed markets. Comparing only the annual expense ratio can therefore understate the true cost of a short-term ETF trade.
Use limit orders and inspect market depth when liquidity is weak. A high screen volume is useful but not the only indicator; underlying basket liquidity and market-maker activity can support an ETF even when recent traded volume is modest. Conversely, a narrow-looking quote for a tiny quantity may widen when the investor submits a large market order.
| Situation | Practical treatment |
|---|---|
| ETF NAV ₹100, bid ₹99.80, ask ₹100.20 | A buy-and-immediate-sell round trip loses about ₹0.40 per unit before brokerage/tax. |
| Large order compared with visible depth | Use limit pricing or split execution; a market order may walk through multiple price levels. |
| ETF price materially diverges from iNAV | Check market timing, stale underlying prices, creation/redemption liquidity and whether the quote is executable. |
Worked example 1
An ETF shows NAV ₹100.00. The best bid is ₹99.70 and best ask ₹100.30. An investor who buys immediately at ₹100.30 and could only sell immediately at ₹99.70 faces roughly a 0.60% round-trip spread before brokerage and taxes, even though the published expense ratio may be far lower. A patient limit order near fair value may reduce the execution cost, but there is no assurance that it fills.
Worked example 2
An investor chooses between two index ETFs. ETF A has a 0.10% expense ratio but a typical ₹0.50 spread on a ₹100 unit; ETF B costs 0.20% annually but trades with a ₹0.08 spread. For a position likely to be sold in a month, ETF B can be cheaper in practice despite the higher expense ratio. For a multi-year holding, tracking difference and recurring expenses become more important. The holding period therefore changes which cost dominates.
Common mistakes to avoid
- Using NAV as if it were a guaranteed exchange execution price.
- Ignoring spread because brokerage is “zero”.
- Sending a large market order into shallow depth.
- Choosing an ETF solely on recent volume without checking tracking and underlying basket liquidity.
Action checklist
- Check best bid and ask, not just last traded price.
- Compare exchange price with current indicative value where meaningful.
- Review order-book depth for the intended quantity.
- Use limit orders when price control matters.
- Separate tracking error from trading spread.
- Be cautious when underlying markets are closed.
- Include spread in total-cost comparison across ETFs.
Records to retain
- Exchange bid/ask and depth at intended trade time
- Latest NAV/iNAV and tracking-difference data
- Expense ratio and scheme factsheet
- Contract note showing actual execution price and charges
Questions users actually ask
What is the difference between NAV and iNAV?
NAV is the fund’s accounting value, usually determined on the prescribed valuation cycle; iNAV is a more frequent indicative reference during trading hours.
Why can ETF price differ from NAV?
ETF units trade on exchange supply/demand. Market makers and arbitrage tend to align price with portfolio value, but temporary premiums/discounts can occur.
Is the lowest expense ratio always the cheapest ETF?
No. Spread, tracking difference, brokerage/taxes and execution quality can dominate for some investors.
Should I use market orders?
For liquid ETFs and small orders they may execute well, but limit orders provide more price control when spread or depth is a concern.
Primary and official sources
- SEBI — Master Circular for Mutual Funds, 20 March 2026
- SEBI Investor — Mutual fund/ETF investor resources
Educational only. Verify official sources before acting.