How ETF Prices Are Determined
Unlike mutual funds, which have a single daily price (NAV), ETF prices fluctuate continuously throughout the trading day. The price you pay for an ETF share is determined by supply and demand on the stock exchange — the same way individual stock prices are set.
But ETFs have an additional mechanism that stocks lack: the creation and redemption process. This system, driven by authorized participants and market makers, keeps ETF market prices tightly aligned with the value of the fund's underlying holdings. It is the engine that makes ETFs work.
The Two Markets: Primary and Secondary
ETFs operate across two interconnected markets:
The secondary market is the stock exchange where you buy and sell ETF shares. This is the market you interact with through your brokerage account. Prices here are determined by supply and demand — buyers bidding and sellers asking.
The primary market is where authorized participants (APs) interact directly with the ETF issuer to create or redeem shares. Individual investors cannot access this market. It exists solely to keep the secondary market functioning properly.
These two markets are linked by arbitrage. When prices in the secondary market drift away from the fair value of the underlying holdings, APs step in to profit from the gap — and in doing so, they push prices back into alignment.
Authorized Participants and Market Makers
Authorized participants are large institutional firms — think Goldman Sachs, JPMorgan, or Citadel Securities — that have agreements with ETF issuers to create and redeem shares. They are the only entities that can transact in the primary market.
Market makers are firms that provide liquidity on the exchange by continuously quoting bid and ask prices. They commit to buying and selling ETF shares throughout the day, ensuring there is always someone on the other side of your trade. Many APs also act as market makers, but they are distinct roles.
Together, APs and market makers keep ETF prices fair and markets liquid. Without them, ETFs would not function as intended. Their profit motive is what makes the arbitrage mechanism self-sustaining.
The Creation Process: Making New ETF Shares
When demand for an ETF pushes its price above NAV (a premium), an AP can profit by creating new shares:
Step 1: The AP buys the underlying securities in the open market (for example, all 500 stocks in the S&P 500 in the correct proportions).
Step 2: The AP delivers this basket of securities to the ETF issuer.
Step 3: The ETF issuer gives the AP a creation unit — typically 25,000 to 50,000 new ETF shares.
Step 4: The AP sells the new ETF shares on the secondary market.
Because the AP bought the underlying securities at NAV but sells the ETF shares at the higher market price, it captures the premium as profit. The additional supply of ETF shares on the market pushes the price back down toward NAV.
The Redemption Process: Removing ETF Shares
When selling pressure pushes an ETF's price below NAV (a discount), the process reverses:
Step 1: The AP buys the underpriced ETF shares on the secondary market.
Step 2: The AP delivers the ETF shares to the issuer in creation-unit-sized blocks.
Step 3: The ETF issuer gives the AP the underlying securities (an in-kind transfer).
Step 4: The AP sells the underlying securities at their market value.
The AP profits from the discount and the reduction in ETF share supply pushes the market price back up toward NAV. This in-kind redemption is also what makes ETFs tax-efficient — no securities are "sold," so no capital gains are triggered.
Premiums and Discounts in Practice
For large, liquid ETFs tracking domestic indexes — like SPY, VOO, or VTI — the arbitrage mechanism keeps prices within a penny or two of NAV. Premiums and discounts are so small they are essentially irrelevant.
Wider gaps can appear in specific situations. International ETFs may trade at apparent premiums or discounts when their underlying foreign markets are closed. The ETF price reflects new information (US market moves, breaking news) while the stale NAV does not, so the "premium" may actually be the more accurate price.
Bond ETFs in stressed markets can also trade at significant discounts to NAV. This happened during the COVID crash in March 2020, when some bond ETFs traded 3%–5% below NAV. Debate continues over whether the ETF price or the NAV was the more accurate reflection of true bond values.
For more on this topic, see our article on ETF premiums and discounts.
What This Means for Individual Investors
The arbitrage mechanism works quietly in the background, and most investors never need to think about it. The practical implications are simple:
Use limit orders when buying or selling ETFs. This guarantees your execution price and protects you from momentary price dislocations. Limit orders are especially important for less liquid ETFs.
Avoid trading at the open and close. Prices are less stable and spreads are wider in the first and last 15 minutes of trading. Mid-day generally offers the best execution.
Check the bid-ask spread before trading. If the spread is unusually wide, it may indicate liquidity issues or market stress. Wait for conditions to normalize if the spread seems too high.
For everyday investors buying and holding popular ETFs, the market price and NAV are close enough that you can simply place a limit order near the current price and not worry further. The arbitrage mechanism handles the rest.
