ETF Rule 6c-11 Compliance Requirements and the Data Behind Them

For an ETF relying on SEC Rule 6c-11, the public website is part of the fund's disclosure process. Publishing a product description and a few headline statistics is only part of the work. The site also needs holdings, daily market information, historical premium and discount information, and a prescribed measure of bid-ask spreads.

Producing those disclosures connects several systems: fund accounting, portfolio records, market data, calculation services and website publishing. An error at the handoff can put the wrong date, number or history on an otherwise functioning page.

This guide explains the main website disclosures and the data work behind them. It also identifies basket and recordkeeping obligations that a website implementation alone does not address.

Start with the fund's regulatory basis

Rule 6c-11 provides exemptive relief for qualifying US ETFs organized as registered open-end management companies. It supports the ETF structure subject to conditions, including website disclosures and basket procedures. The fund's regulatory basis determines which requirements apply; a product operating under separate exemptive relief may have different conditions. SEC adopting release.

Use the current rule, not an unamended launch-era summary, when establishing scope. For example, the current provision addresses leveraged and inverse index ETFs by requiring compliance with applicable provisions of Rule 18f-4. An older statement that Rule 6c-11 simply excludes all such ETFs does not reflect that amendment. Current Rule 6c-11, paragraph c4.

What the website needs to disclose

The disclosures must be prominent, publicly available and free of charge. The principal categories are:

• Portfolio holdings: prior-business-day closing holdings supporting the next NAV calculation, published before regular trading opens on the primary listing exchange. Required fields, where applicable, are ticker, CUSIP or another identifier, holding description, quantity and portfolio weight.
• Daily market information: the previous business day's NAV per share, market price and premium or discount.
• Historical premiums and discounts: a table counting days at a premium or discount, plus a line graph of deviations, for the most recently completed calendar year and completed calendar quarters since then, or the fund's shorter life.
• Median bid-ask spread: the rolling 30-calendar-day figure calculated using the rule's specified methodology.
• Persistent deviations: additional disclosure when a premium or discount exceeds 2% for more than seven consecutive trading days, explaining the reasonably believed contributing factors.

The SEC's compliance guide explains these categories. Importantly, holdings disclosure concerns the portfolio; a creation or redemption basket is not automatically a substitute. Read the guide alongside the current rule, including subsequent amendments. SEC compliance guide.

Map each output to its source data

The following is an implementation map. It distinguishes the published result from the data needed to produce or validate it.

Keep official inputs separate from derived outputs. For NAV, a publishing service will generally consume the fund's approved accounting result. Reconstructing NAV would require the appropriate asset valuations, liabilities and shares outstanding, with reconciliation to fund accounting; a holdings file alone is insufficient.

Similarly, consume approved portfolio weights where available. Recreating them can require valuation, currency and instrument-specific treatment. Do not assume a simple quantity-times-price calculation describes every derivative, cash balance or other position.

Calculate premiums and discounts with matched observations

The premium or discount calculation is:

Premium or discount percentage = 100 × (market price − NAV per share) ÷ NAV per share.

The rule defines market price as the official closing price, or an NBBO midpoint at the NAV calculation time if that more accurately reflects the share's market value. This is a defined choice, not permission to substitute an arbitrary last trade or an intraday indicative value. SEC adopting release on website disclosures.

For illustration, a $25.10 market price and a $25.00 NAV produce a 0.40% premium. A $24.90 price against the same NAV produces a 0.40% discount. The source prices must correspond to the approved convention and observation date.

Preserve calculation precision before formatting. Classify historical observations using the underlying values; a small nonzero deviation can display as 0.00% after rounding. Missing prices or NAVs should raise an exception rather than generate a zero deviation. Track revisions so an amended source observation can update affected historical outputs.

Calculate the rolling median spread from NBBO data

The prescribed calculation uses national best bid and offer observations at the end of each 10-second interval during each trading day in the last 30 calendar days. For each sample, divide offer minus bid by the NBBO midpoint, then take the median across the sampled relative spreads. Express the result as a percentage rounded to the nearest hundredth. SEC adopting release and paragraph c1v.

In calculation terms:

Sample midpoint = (national best bid + national best offer) ÷ 2.

Sample relative spread = (national best offer − national best bid) ÷ sample midpoint.

Published spread percentage = 100 × median of the sampled relative spreads, rounded as required.

For an illustrative sample with a $24.99 bid and $25.01 offer, the midpoint is $25.00. The relative spread is 0.0008, or 0.08%, equivalent to eight basis points. That sample is one input; it is not the completed 30-day disclosure.

An end-of-day quote cannot supply the prescribed intraday observations. Nor can daily traded volume, OHLC bars or the issuer's NAV feed. The data service needs historical NBBO coverage or sufficient underlying quote data to reconstruct the required observations. A single venue's best bid and offer should not be assumed to be the national best prices.

Take the median across the underlying sample series. A median of daily medians need not give the same result. The SEC's adopting release explains the choice of NBBO, fixed sampling intervals and the median methodology. SEC adopting release on median bid-ask spreads.

Document how the implementation handles timezones, exchange sessions, early closes, trading halts, missing quotes and locked or crossed observations. These are operational methodology decisions requiring appropriate review; the rule's formula should not be presented as a complete specification for every data exception. Apply checks before silently dropping observations or filling gaps.

Maintain history and monitor persistent deviations

Keep the daily deviation series behind the historical table and graph. The completed-period presentation rolls forward as quarters and years end; it is not simply a trailing 12-month chart. The adopting release discusses quarterly updates to that historical presentation, alongside daily current premium or discount disclosure. SEC adopting release on historical presentation.

For the persistent-deviation disclosure, more than seven consecutive trading days means the threshold is reached on the eighth qualifying day. The explanatory notice must remain on the website for at least a year after first posting; ongoing circumstances can require further current disclosure. SEC website posting guidance.

As an operating control, retain signed, unrounded deviations and track premium and discount runs separately under the fund's approved methodology. Use a trading calendar, distinguish missing observations from nonqualifying days, and assign a person to review and approve the explanation. An automated alert can identify a potential trigger; it should not invent the reasons for the deviation.

Website publishing does not cover the whole rule

ETFs must also adopt basket-construction and acceptance procedures, with additional parameters and designated reviewer roles for custom baskets. The rule requires retention of AP agreements and specified exchanged-basket records for at least five years, with the first two years easily accessible. Those records include basket details, custom-basket information where applicable, cash balancing amounts and the transacting AP. Rule 6c-11 paragraphs c3 and d.

A useful website audit trail should separately preserve source references, calculation versions, approved outputs and publication evidence. That is an operational recommendation, not a claim that paragraph d independently imposes the same five-year retention rule on every quote sample or website screenshot. Set retention for those materials with the fund's compliance and records requirements.

Connect calculations to a controlled publishing process

An issuer should be able to trace a displayed number to its source and see whether the expected update reached the public page. Build the workflow around four questions: Did the input arrive? Did it pass validation? Was the calculation approved? Did the correct result publish?

Useful controls include date reconciliation, completeness checks, calculation fixtures, exception alerts and a record of corrections. Confirm publication from the public-facing page, including any cache, rather than treating a successful database write as proof of disclosure. License checks also belong in the workflow: access to historical quotes and permission to display derived outputs need to fit the intended use.

ETF Engine brings issuer websites, fund-data integration and analytics into the same implementation discussion. For a Rule 6c-11 project, the starting point is to map the fund's approved requirements to its actual sources and publishing process, then agree on the calculation, monitoring and support scope.

Reviewing your ETF disclosure workflow? Talk to ETF Engine about fund data, calculations and website delivery.

This article addresses US Rule 6c-11 and related data operations. Applicability, interpretations and the fund's complete obligations should be established with its compliance and legal advisers. Rule text and guidance were checked on October 21 2026.