Why an ETF's price, NAV and holdings differ between sources

How it works

An ETF has two markets and one portfolio. On the exchange, anybody buys and sells shares from anybody else at whatever price they agree. Off the exchange, a small set of firms deal with the fund itself. Rule 6c-11, the SEC rule most US ETFs operate under, calls them authorised participants: members of a registered clearing agency with a written agreement allowing them to place orders for creation units, blocks of ETF shares the fund issues or redeems in exchange for a basket of securities plus a cash balancing amount.

That second market is what ties the price to the portfolio. The SEC's 2019 adopting release describes it: if shares trade below NAV, an authorised participant can buy them on the exchange, assemble a creation unit and redeem it for the more valuable basket; at a premium the trade runs the other way. Buying the cheap side and selling the dear one pushes the two together. It is an incentive, not a guarantee — which is why the price and NAV are two numbers, and why the rule makes the fund publish how far apart they were.

Three figures come out of this, each with its own clock:

• NAV per share — in iShares' words, "the price per share at which each fund issues and redeems shares", calculated by the fund accountants at the close of regular trading, normally 4 p.m. Eastern, every day the New York Stock Exchange is open. Once a day, and only then.
• Market price — set continuously on the exchange. For disclosure Rule 6c-11 defines it as the official closing price, or, where it more accurately reflects value at the moment NAV is struck, the midpoint of the national best bid and offer at that time.
• An intraday value estimate — iNAV, IIV or IOPV, depending on who is publishing it. Not required by the rule, and not computed by the same people as the NAV.

Three numbers, read on one page

The iShares Core S&P 500 ETF's own page, read on 8 October 2026, showed a NAV of $780.82 and a closing price of $780.58, both as of 7 October, and a premium/discount of −0.03%. That is the gap between those two numbers as a percentage of NAV — the definition Rule 6c-11 uses.

The same page explains why even that small gap exists. NAV is struck at 4 p.m.; the closing price is the last trade, and iShares notes that "the date/time of the last trade sometimes may occur before 4:00 p.m. eastern time", so "ongoing price discovery may result in a deviation" between the two. Its premium/discount chart describes market price differently again — "the midpoint between the highest bid and the lowest offer on the listing exchange, as of the time that the Fund's NAV is calculated". Both are permitted by the rule. A third-party site that shows a premium for the same fund may be using either, or the last trade it happened to receive, and will rarely say which.

The same page carried four as-of dates: NAV, price and number of holdings as of 7 October, sector weights and P/E as of 6 October, and the 30-day SEC yield and 12-month trailing yield as of 31 August. Every figure on an ETF page has a date, and they are not the same date.

iNAV: an estimate the SEC chose not to require

Before Rule 6c-11, ETFs ran on individual exemptive orders, and those orders required an intraday indicative value. The 2019 adopting release records that exchange listing standards then required it at least every 15 seconds during regular trading, and that it also goes by iNAV and PIV.

The Commission did not carry the requirement into the rule, and its reasons are the reasons an iNAV on a quote screen can mislead:

• It "can be stale or inaccurate for ETFs with foreign securities or less liquid debt instruments", because it is built from last available quotations while NAV uses fair value when quotations are not readily available.
• For funds holding fast-moving securities, dissemination lags mean it can trail the market instead.
• "Because there are no uniform methodology requirements, the IIV also can be calculated in different and potentially inconsistent ways."
• Market makers and authorised participants, the release says, no longer use it to evaluate arbitrage for fully transparent ETFs. They compute their own intraday values from the published daily holdings and use the IIV as a secondary or tertiary check.

So an iNAV is one party's estimate, on one methodology, at one refresh rate. When a site shows an ETF trading at a "premium to iNAV" during the day, the premium may be in the estimate.

Premiums and discounts that are not mispricing

Some gaps are structural. The adopting release says an ETF investing in foreign securities "may be more likely to experience a persistent deviation between market price and NAV per share given that many foreign markets are closed during the U.S. trading day", and more so when that market is closed for an extended period. A fund holding Japanese or European shares trades in New York while its holdings' last prices are hours old; the ETF's price is the market's live estimate, and the NAV is computed from those older prices or a fair-value adjustment to them. Bond ETFs have a version of the same problem, because many bonds do not trade every day.

Rule 6c-11 makes the fund disclose the history rather than explain it away. Each business day the website must show NAV, market price and premium or discount as of the prior business day; a table and line graph of premiums and discounts over the last calendar year and the quarters since; and the median bid-ask spread over the last 30 calendar days, computed from the national best bid and offer every ten seconds. If the premium or discount exceeds 2% for more than seven consecutive trading days, the fund must say so and discuss the factors believed to have caused it, and leave that statement up for at least a year.

That page on the issuer's site is the primary record. Any other source is a copy of it or its own calculation.

When holdings are published, and by whom

There are two publication regimes, and they are years apart in speed.

The issuer, every business day. Rule 6c-11 requires an ETF relying on it to disclose on its website, before the opening of regular trading, each holding that will form the basis of that day's NAV calculation — ticker, CUSIP or other identifier, description, quantity and percentage weight — and those holdings must be the portfolio as of the close of the prior business day. This is a condition of the rule, not a courtesy — and only for ETFs that rely on it, which not every ETF does (see below). What is voluntary, according to the SEC's 2026 proposal, is the monthly holdings some registered funds post on their websites or sell through aggregators on a lag of 15, 30, 45 or more days.

The SEC, from Form N-PORT. Registered funds, including ETFs, report holdings to the SEC on Form N-PORT. Under the requirements in force on 8 October 2026, monthly reports are filed within 60 days of the end of each fiscal quarter, and only the report for the quarter's third month is made public, upon filing. A fund may also report up to 5% of its investments as "miscellaneous securities", which can stay nonpublic for up to a year.

That second regime is being rewritten, and has not settled:

1. August 2024. The SEC adopted amendments requiring each monthly report within 30 days of month end and making every month public 60 days after month end (Release No. IC-35308, 28 August 2024).
2. April 2025. It delayed them to 17 November 2027 for fund groups with $1 billion or more in net assets, and 18 May 2028 for smaller groups (Release No. IC-35538, 16 April 2025).
3. February 2026. On 18 February 2026 it proposed going back: 45 days to file each monthly report, and publication restored to the third month of each fiscal quarter, 60 days after quarter end (Release No. IC-35962, published 23 February 2026). The stated reason includes reducing the risk of outsiders inferring a fund's trading intentions from its reports.
4. 8 October 2026. The SEC's rulemaking page for the proposal lists the proposal, its Federal Register publication and a comment deadline of 24 April 2026, and no final rule.

For daily-disclosing ETFs none of this changes what you can see: the proposal states that its discussion of publication frequency does not relate to ETFs required to disclose holdings daily under Rule 6c-11, because N-PORT changes do not affect how often those funds' holdings are made public. It matters for mutual funds, for ETFs outside the rule, and for anybody whose holdings data comes from EDGAR. How to get ETF holdings as data covers pulling both files and what each leaves out.

ETFs outside the daily rule

Rule 6c-11 has a boundary. The adopting release lists the ETFs it did not cover as adopted (p. 17 of the SEC's copy): those organised as unit investment trusts, leveraged and inverse ETFs, ETFs structured as a share class of a fund with other classes, and actively managed ETFs that do not provide daily portfolio transparency — non-transparent ETFs, which "would not meet the conditions of rule 6c-11" and continue under their own exemptive orders. On share classes it is explicit (p. 122): absent separate relief, such an ETF "cannot operate in reliance on rule 6c-11." The current rule text separately addresses leveraged and inverse ETFs, which must also comply with Rule 18f-4.

Outside the rule means not required to publish daily, which is not the same as not publishing. Two S&P 500 funds, read on 8 October 2026:

• SPY is a unit investment trust, as State Street's own page says. That page showed fund top holdings as of 7 October and offered a full holdings download marked "Daily".
• VOO is, in Vanguard's words, "an exchange-traded share class of Vanguard 500 Index Fund". Its page showed holdings as of 31 August 2026 — with earlier month ends to choose from — beside a closing price and NAV as of 7 October. Vanguard's disclosure policy promises a daily list only for "certain actively managed Vanguard ETFs and certain Vanguard index ETFs", and says the holdings it shows are "provided on a delayed basis".

So the date beside the holdings tells you which regime you are looking at, and for a fund outside the rule the issuer, not the SEC, decides how old it is.

European UCITS ETFs sit outside Rule 6c-11 altogether, and their rule is a policy rather than a frequency. ESMA's guidelines on ETFs and other UCITS issues (paragraph 17) require a UCITS ETF to disclose in its prospectus, key investor information and marketing material "the policy regarding portfolio transparency and where information on the portfolio may be obtained". The Central Bank of Ireland, which authorises most of them, spells out the two permitted policies in its UCITS Q&A (ID 1012, 42nd edition, 17 April 2025): daily disclosure, made available on a non-discriminatory basis, or periodic disclosure, under which "appropriate information" goes daily to authorised participants and market makers to keep the arbitrage working, investors have a documented way to request portfolio information, and the holdings as at the end of each calendar quarter are published within 30 business days of the quarter end. Which policy a fund runs is in its prospectus, and a research site can be slower than either: in the section below, justETF updates the iShares MSCI World composition once a month. A holdings file for a periodic-disclosure fund is a quarter-end list however fresh the page that shows it.

For non-transparent ETFs the arbitrage problem is solved another way. For one model, Managed Portfolio Shares, an NYSE Arca filing quotes the Commission: the portfolio holdings "are not publicly disclosed on a daily basis"; a verified intraday indicative value, or VIIV, is disseminated "in one second intervals during Regular Trading Hours"; and like other registered funds each series must disclose its holdings "on a quarterly basis, within at least 60 days following the end of every fiscal quarter". The SEC's 2026 proposal describes these funds as "a small number".

If a research site shows a non-transparent ETF's holdings, they are a quarter-end portfolio up to two months old, whatever date the page is dated.

Why two holdings files for one ETF disagree

Assume both files are honest. They still differ, for four reasons, in the order worth checking.

The as-of date. An issuer file published before today's open is yesterday's close. A vendor's file may be a month end or a quarter end, and an N-PORT report is the last day of a fiscal quarter that belongs to the fund rather than the calendar. Compare the dates before you compare a single weight.

Cash, futures and the lines that are not stocks. An index fund equitises cash with futures: the iShares S&P 500 page says exchange-traded index futures "may be used to offset cash and receivables for the purpose of tracking the benchmark index". Whether a source shows that contract, nets it into cash, or drops it changes every weight beside it. Swap-based, leveraged and options funds are worse: a contract's market value and the exposure it creates are different numbers, and sources choose differently between them.

Share count versus weight. Rule 6c-11 makes the issuer publish both quantity and weight, and only the quantity is an observation. A weight is a quantity multiplied by a price, divided by a total, and the price is a choice. The iShares holdings disclaimer is explicit: market value, weight and notional value are "based off of a price provided by a third-party pricing vendor" that is "not necessarily the price at which the Fund values the portfolio holding for the purposes of determining its net asset value"; the holdings shown reflect the investment book of record, which "may differ from the accounting book of record"; and for non-US holdings the exchange rate for the vendor price is generally taken at 4 p.m. London, while the valuation price uses the New York close. One issuer, two sets of prices, two exchange-rate fixings, on the same day.

Fund versus share class. A ticker is a share class, and holdings belong to the fund. Where an ETF is one class of a fund that also has mutual-fund classes, the regulatory holdings are the whole fund's. The how-to linked above has the case in detail.

Which file each research site reads. For SPY on 8 October 2026, with the issuer's fund holdings dated 7 October: ETF.com credits FactSet as the data provider on each section of its page. Trackinsight dated its holdings "08/31/26", 500 positions, beside a price as of 5 October. ETF Research Center printed no as-of date on its top holdings and counted 494 holdings, against 503 constituents in the index on the issuer's page as of 6 October. ETF Insider says most of its data comes from SEC EDGAR and that its holdings update with the filings, which "are made every quarter". justETF, for the iShares Core MSCI World UCITS ETF, dated its holdings 31 August 2026; it says composition is "updated once a month", shows it only for ETFs that physically track their index, and names Trackinsight, FactSet and Xignite among its data providers.

What you can do about it

Name the clock before you name the number. For any price, NAV, premium or weight, find the as-of date and time next to it. If a source prints none, it is not a source for a decision that depends on the difference.

Use the issuer's page as the reference for a Rule 6c-11 ETF. It is required to publish the prior day's holdings before the open, plus NAV, market price, premium or discount, the median spread and the premium history. Every third-party figure for that fund is a copy of that page or a computation from it, older or not. For a unit investment trust or a share-class ETF, the issuer's page is still the reference, but read the date beside its holdings first: it may be a month end.

Read a premium on an international or bond ETF as a timing gap first. Check the fund's premium history table on its own site: a fund that sits at a premium every day the underlying market is closed is showing you its structure, not a bargain or a warning. The 2% for seven days disclosure is where the rule starts asking for an explanation.

Treat an iNAV as one estimate among several. Ask whoever publishes it what it is built from — the creation basket or the index, and how often it refreshes. The SEC's own position is that it can be stale and that there is no uniform method.

Before comparing two holdings files, align four things. The as-of date; whether cash and derivatives are lines, netted or dropped; whether you are comparing share counts or weights, and if weights, at whose prices; and whether the figure is the fund's or a share class's. Compare share counts on the same date first. If those match, the weights differ only because of price.

For a holdings history, do not wait for monthly N-PORT. Publication is quarterly on 8 October 2026, monthly publication is delayed to November 2027 at the earliest, and the SEC has proposed keeping it quarterly. A dated archive of daily issuer files is something you start collecting yourself or buy. For overlap and look-through, ETF research tools differ mainly in which of these files they read and how old it is — ETF Research Center and ETF Insider are compared on exactly that.