How ETF creation and redemption works: the basket swap that pins price to NAV

How ETF creation and redemption works is a primary-market “wrap and unwrap” process where an authorized participant swaps a daily-published basket of underlying assets plus a small cash plug for a large block of ETF shares, then reverses it to remove shares. That repeatable trade is the arbitrage mechanism that usually keeps the exchange price close to NAV, until underlying liquidity or access breaks and premiums or discounts can widen.

Key Takeaways

• Creation and redemption happens in the primary market between the issuer and an authorized participant, not between ordinary investors on an exchange.
• The issuer publishes a daily “portfolio deposit” recipe that generally mirrors holdings plus a small cash amount, and APs transact in big blocks called a creation unit, often cited as 50,000 shares.
• ETF creation redemption is an arbitrage mechanism: APs tend to create into premiums and redeem into discounts, which is why the wrapper usually stays close to NAV.
• In kind redemption versus cash creation changes friction and tax outcomes, and spot crypto ETPs are a clean example after the SEC permitted in-kind creations/redemptions on July 29, 2025.

How ETF shares are issued and removed

ETF share count is elastic. When demand shows up on the exchange, new shares can be introduced. When supply overwhelms bids, shares can be pulled out of circulation. That supply adjustment does not happen because the fund sponsor is “issuing stock” the way an operating company does. It happens because the ETF wrapper can be assembled and disassembled against the underlying portfolio.

The key split is venue. Retail and most institutions trade ETF shares in the secondary market, where price is whatever buyers and sellers agree to intraday. The SEC’s 2001 concept release is explicit that ETFs do not sell or redeem individual shares at NAV. They only transact at NAV in large blocks, while individual shares trade on exchanges at market prices throughout the day.

Those large blocks are the primary market interface. The sponsor and a small set of counterparties exchange the underlying basket for ETF shares, or ETF shares for the underlying basket. State Street frames creation as “wrapping” the underlying securities into the ETF structure and redemption as “unwrapping” the ETF back into the individual securities.

This is why the phrase “ETF trades at NAV” is sloppy. NAV is a reference value for the basket. The exchange price can print above or below it, and the whole point of the primary-market plumbing is to make that gap an executable trade for the firms that can actually do the swap.

Who authorized participants are and do

The system runs through a narrow door: the authorized participant. State Street describes APs as US registered, self-clearing broker-dealers that regulate the supply of ETF shares in the secondary market. That “self-clearing” detail matters because the job is operationally heavy: source the basket, deliver it, receive shares, and then distribute those shares into the exchange ecosystem.

APs are not the same thing as market makers. ETF Stream draws the line cleanly: market makers match buyers and sellers on the stock exchange, while authorized participants can step into the primary market to create or redeem shares with the issuer. A market maker can quote all day without ever touching the issuer. An AP has the special pipe.

What APs actually do is run a repeatable basis trade in size. When the ETF is rich versus its basket, the AP can create shares at NAV and sell them at the higher market price. When the ETF is cheap, the AP can buy shares in the market and redeem them at NAV for the underlying. The incentive is the spread, not a mandate. ETF Stream notes APs are not obliged to create and redeem, which is the first clue to when the mechanism can get stressed.

Crypto readers will see this discussed under authorized participants and market makers crypto etfs, because the same division of labor shows up in spot Bitcoin and Ethereum ETPs. The wrapper trades on an exchange. The AP pipe is where supply is manufactured or destroyed.

The step by step creation process

Creation starts with a recipe, not a vibe. The SEC concept release describes a “Portfolio Deposit” announced at the beginning of each business day. It generally mirrors the ETF’s portfolio and typically includes a small amount of cash to true-up the difference between the basket value and the NAV of the shares being created.

Then the block size kicks in. Both the SEC and State Street use the same canonical example: ETF shares are created in large blocks called a creation unit, often cited as 50,000 ETF shares. That block is why small retail flow does not directly “create shares.” Retail flow moves the exchange price. The primary market responds only when the spread is worth compressing in institutional size.

A clean creation sequence looks like this:

1. The issuer publishes the daily portfolio deposit basket and any small cash amount needed to balance to NAV. 2. An authorized participant assembles the underlying securities in the required weightings to reach creation unit size. 3. The AP delivers that basket to the ETF sponsor and receives the creation unit of ETF shares. 4. Those newly created shares are introduced to the secondary market, where they can be sold to meet demand.

State Street’s framing is blunt: when demand increases, more shares can be created using this process, and the liquidity of the underlying securities can enhance the liquidity of the ETF itself.

For crypto ETPs, the same logic applies, but the operational choice is whether the creation leg is done as cash creation or as an in-kind transfer of the underlying asset. That distinction is where costs and tracking error start to show up on a trader’s screen.

The step by step redemption process

Redemption is the reverse pipe, and it is how the market removes excess shares without the fund manager dumping the portfolio into the market. State Street describes APs collecting large increments of ETF shares in the secondary market and delivering them to the sponsor in exchange for the underlying securities in the appropriate weightings, again typically 50,000 shares.

A standard redemption sequence runs like this:

1. The authorized participant buys ETF shares in the secondary market until it has a redemption unit, typically the same size as a creation unit. 2. The AP delivers those shares to the issuer in the primary market. 3. The issuer delivers the underlying basket back to the AP in the appropriate weightings. 4. The redeemed ETF shares are removed from circulation, reducing supply on the exchange.

This is where the “wrapper” metaphor earns its keep. Creation wraps the basket into shares. Redemption unwraps shares back into the basket. The portfolio manager is not the one leaning on the bid every time someone sells the ETF. State Street notes that because of the creation and redemption process, the ETF’s portfolio manager typically does not need to buy or sell securities except for rebalancing purposes.

For crypto products, the redemption leg is where in kind redemption versus cash redemption becomes more than semantics. A cash-only redemption forces the fund to sell the underlying to raise cash. An in-kind route hands the underlying out directly. Phemex reports that spot crypto ETFs initially used cash-only creations/redemptions and that the SEC later permitted in-kind creations/redemptions for Bitcoin and Ethereum ETPs on July 29, 2025, shifting the plumbing toward the commodity-ETF model.

Why creation redemption keeps prices aligned

The price anchor is not “ETF magic.” It is how etf arbitrage keeps price near nav: a premium or discount becomes a trade that can be executed in the primary market at NAV-sized terms. State Street and ETF Stream both describe the same behavior pattern. When a premium develops, APs create shares to meet demand and push the price back toward fair value. When a discount develops, APs buy shares and redeem to reduce supply.

That is the arbitrage mechanism, and it is why ETF spreads are often tighter than the underlying would suggest. But the mechanism only works when the underlying basket is tradable and hedgeable. ETF Stream flags the failure mode directly: during periods of rapidly vanishing liquidity, markets can be difficult to access or there may be zero liquidity in the underlying holdings. APs are not obliged to step in, so the spread has to compensate them for the risk and the operational cost.

Liquidity also has two layers, and confusing them is expensive. State Street describes ETF liquidity as (1) secondary-market liquidity in the ETF shares and (2) liquidity of the underlying securities. This is why “ETF liquidity = ETF trading volume” is a trap. A high-volume ETF can still be a bad execution venue if the underlying basket is illiquid or inaccessible at that moment.

Finally, in-kind versus cash is not a footnote. State Street says creation/redemption transactions are typically conducted in-kind and describes them as tax exempt, supporting ETF tax efficiency. Phemex’s crypto example shows why the market cares: cash-only routes add extra conversions between the wrapper and the underlying. That is the core of in kind vs cash redemption crypto etfs, and it is also why the July 29, 2025 SEC decision mattered for spot Bitcoin and Ethereum ETP mechanics.

Limits and real world frictions

The clean model assumes the AP can source the basket, hedge it, and clear it. When any of those inputs break, the wrapper can gap versus NAV. ETF Stream points to the exact stress point: rapidly vanishing liquidity or zero liquidity in the underlying holdings. In those moments, the premium or discount is not a “pricing error.” It is the market repricing the cost and risk of doing the create/redeem trade.

March 2020 is a useful reference because it was a broad liquidity shock where ETF plumbing got tested. ETF Stream notes the sell-off in March 2020 proved the resilience of the ETF structure and increased AP involvement. The lesson is not that gaps never happen. The lesson is that the AP pipe is a capacity constraint, and the market will pay for it when everyone wants out at once.

Product rules also matter. The SEC’s 2001 concept release spends real time on the fact that ETFs needed exemptive relief to operate with creation units and secondary-market trading at negotiated prices. That history is why crypto ETP structure debates keep resurfacing. The question is not just what the ETF holds, but what the rules allow the AP to deliver and receive.

Crypto adds another layer: spot versus futures exposure changes what the “basket” even is. A spot product’s basket is the underlying asset. A futures product’s basket is futures positions and collateral mechanics. That distinction is the heart of what is a crypto etf spot vs futures, and it feeds directly into how reliably an AP can run the arbitrage loop.

The practical read when a premium or discount looks weird is simple: can an AP actually execute the basket trade right now, and on what terms. If the answer is “not cleanly,” the wrapper can trade like a closed-end vehicle for longer than most retail investors expect.

The Take

I’ve watched too many traders talk about ETF pricing like it’s a law of physics, then get surprised when the wrapper prints a real premium or discount. The mechanism is only as good as the ability of an authorized participant to source and hedge the basket. ETF Stream’s point that APs are not obliged to create or redeem is the part that should be taped to the monitor.

The cleanest mental model is the daily recipe plus the block size. The SEC’s portfolio deposit basket and the 50,000-share creation unit are the whole game. When the underlying is liquid and accessible, the spread becomes an executable trade and the arbitrage mechanism does its job. When access or liquidity breaks, the trade stops being “free money,” and the ETF can trade like a stressed wrapper until the basket is tradable again.

Sources

• State Street Global Advisors
• U.S. Securities and Exchange Commission
• ETF Stream
• Phemex