# ETF Research Tools — Screeners, Overlap, Holdings and Flows

ETF screeners and fund-analysis tools compared on what decides the choice — total cost, holdings overlap, US or UCITS listings, data freshness and paywalls.

*https://stockmarketstack.com/categories/etf-research*

People arrive at this section with one of four questions, and different tools answer each. If you
are **choosing between two index funds on the same benchmark**, the expense ratio decides less
than you think: compare total cost and tracking difference, which
[Trackinsight](https://stockmarketstack.com/tools/trackinsight) prints for free and
[ETF Research Center](https://stockmarketstack.com/tools/etf-research-center) turns into a cost comparison. If you **hold
several funds and suspect they own the same stocks**, you need holdings-based overlap. If you are
**a European buyer choosing UCITS funds**, most of the US-built tools here do not list a single
fund you can buy. And if you are **watching where the money is going**, flows are published daily
and free in more places than the paywalls suggest.

- **Total cost of two funds, not just the fee** — [ETF Research Center](https://stockmarketstack.com/tools/etf-research-center)'s TCO tool, [Trackinsight](https://stockmarketstack.com/tools/trackinsight) for tracking difference.
- **Overlap between two funds** — [ETF Research Center](https://stockmarketstack.com/tools/etf-research-center), free with a login.
- **Overlap across a whole portfolio** — [ETF Insider](https://stockmarketstack.com/tools/etf-insider), US-listed funds, $14 a month for full holdings.
- **UCITS funds and European savings plans** — [justETF](https://stockmarketstack.com/tools/justetf); [Trackinsight](https://stockmarketstack.com/tools/trackinsight) for global listings side by side.
- **Free screener and flows for US-listed funds** — [ETF.com](https://stockmarketstack.com/tools/etf-com).
- **Daily flows with look-through behind them** — [ETF Action](https://stockmarketstack.com/tools/etf-action), from $29 a month.
- **Ranking funds by trend and backtesting a rotation** — [ETFreplay](https://stockmarketstack.com/tools/etfreplay).

## Two jobs: ranking funds, and opening one up

The listing splits along the two things these tools do. A **screener** ranks funds against each
other — on cost, size, performance, or for [ETFreplay](https://stockmarketstack.com/tools/etfreplay) on relative strength —
and is how you get from several thousand funds to five. **Analytics** opens a fund up: what it
holds, how much of that another fund also holds, and money moving in and out. Most products lean
one way. ETF.com, Trackinsight, justETF and ETFreplay are screeners first; ETF Research Center,
ETF Insider and ETF Action are bought for what they show inside a fund.

What none of them sells is an answer to "which fund should I buy". ETF Research Center prints its
own forward-return score and a five-step label from Speculative to Avoid on every fund page, and
says how it is calculated; read it as one model's output, not as a fact about the fund.

## The expense ratio is the smallest number on the bill

**The expense ratio** is the fee the issuer deducts, and the only cost most screeners sort by. It
is not what you pay. Three other costs sit beside it and none is on the label.

**The spread** is paid on every purchase and sale. ETF Research Center averages each fund's
bid/ask spread from NBBO observations over up to three months, and its TCO tool adds that and a
round-trip commission to the fee over a holding period you choose — the comparison a long-term
buyer of a thinly traded fund needs and a fee sort hides. ETF.com's fund pages print the daily
spread and the maximum premium or discount to NAV.

**Tracking difference** is how far the fund actually trailed its index over a period, and it
absorbs everything at once: the fee, [withholding tax](https://stockmarketstack.com/glossary/dividend-withholding) on the
dividends the fund receives, securities-lending income, cash held between distributions.
Trackinsight puts the one-year figure on every comparison page. On 7 October 2026, SPY against IVV
read a TER of 0.0945% against 0.03%, and a one-year cumulative return difference of roughly −10 to
−14 basis points for SPY against −3 to −4 for IVV. ETF.com's analysis of SPY names one reason: as a
unit investment trust it cannot lend securities or reinvest dividends between distributions.

**Withholding** matters most when the fund and the shares it holds are in different countries,
which is the normal case for a UCITS fund holding US stocks. No tool in this listing models it
directly; it shows up only inside tracking difference, which is a reason to compare that rather
than the fee.

## Overlap is computed from holdings

Two funds with different names and different index providers can hold nearly the same thing.
Overlap tools measure it, and they measure it from holdings, not from returns.

[ETF Research Center](https://stockmarketstack.com/tools/etf-research-center) does it pairwise and by weight: for each stock
both funds hold it takes the smaller weight and sums them. SPY against QQQ came to 54% on 7 October
2026, across 85 shared names — 84% of QQQ's holdings were in SPY, only 17% of SPY's were in QQQ,
which is why overlap is not symmetric and a single percentage needs reading carefully. The tool is
equity-only. [ETF Insider](https://stockmarketstack.com/tools/etf-insider) does the same job for a whole portfolio of ETFs,
mutual funds and stocks at once, with a matrix of pairwise overlap and concentration by name,
sector and country. [Trackinsight](https://stockmarketstack.com/tools/trackinsight) lists holding overlap among its portfolio
analytics, but the full version is in its institutional product.

The reverse lookup is just as useful: enter a stock and see which funds hold it. ETF Research
Center, ETF.com and Trackinsight all offer one — Apple sat in 729 funds on ETF Research Center's
count.

## US-listed and UCITS are different universes

A fund tracking the S&P 500 exists several times over — SPY and VOO in New York, VUAA in Europe,
others in Toronto, Sydney and Seoul — and a European investor generally buys the UCITS version.
Coverage decides which tools are any use before features do.

**US-listed only:** [ETF.com](https://stockmarketstack.com/tools/etf-com) (5,871 funds in its screener on 7 October 2026),
[ETF Action](https://stockmarketstack.com/tools/etf-action), [ETFreplay](https://stockmarketstack.com/tools/etfreplay) (about 1,500, and only funds past
roughly $250 million in assets) and [ETF Insider](https://stockmarketstack.com/tools/etf-insider).

**UCITS and US together:** [Trackinsight](https://stockmarketstack.com/tools/trackinsight) screens 15,875 funds across listing
venues and adds French PEA eligibility and UK reporting status to its comparisons;
[ETF Research Center](https://stockmarketstack.com/tools/etf-research-center) screens US, Canadian and UCITS universes.

**UCITS only:** [justETF](https://stockmarketstack.com/tools/justetf), whose domicile filter does not include the United
States, and whose savings-plan filter has no US equivalent because the product does not exist
there.

## How old the holdings are

Prices and flows on these sites are daily. Holdings usually are not, and the gap is rarely
printed where you would look for it.

On 7 October 2026 Trackinsight's SPY page carried prices and flows as of the previous close and
holdings and sector weights stamped 31 August — while the same comparison page's text described
those figures as "as of yesterday". [ETF Insider](https://stockmarketstack.com/tools/etf-insider) takes most of its holdings
from quarterly SEC filings, which the regulator allows up to 60 days after quarter end, so an
overlap figure there can describe a portfolio as it stood months ago. ETF Research Center
standardised performance as of 30 September and valued funds on the latest close.

Freshness is not the only data problem. ETF.com's screener, on FactSet data, listed IVV's expense
ratio as 10% the same day — a fund that charges 0.03% — which would put it last in any cost sort.
Issuers publish full holdings every business day on their own sites; for a decision that rests on
one number, that is the copy to check. [How to get ETF holdings as data](https://stockmarketstack.com/how-to/get-etf-holdings-as-data)
covers the daily files and the SEC's quarterly ones.

## What free covers, and where the paywall starts

More is free here than in most of the catalogue, because several of these sites are paid for by
advertising and by the fund industry rather than by readers.

- **Free with no account:** ETF.com's screener, flows, comparisons and fund pages; Trackinsight's
  screener and two-fund comparisons; ETF Research Center's fund pages and the first five rows of
  its overlap and stock-locator results; ETFreplay's screener over the 100 largest funds.
- **Free with a login:** the full overlap and locator lists on ETF Research Center; flows,
  exposures and watchlists on Trackinsight; ETF.com's AI assistant.
- **Where money starts:** ETF Insider Pro at $14 a month or $99 a year for full holdings;
  justETF Premium from 9.90 € a month on annual billing, for portfolio tools rather than data;
  ETF Research Center at $29 a month for fundamentals and full holdings; ETF Action at $29 with
  Excel capped at 50 rows; ETFreplay at $29.99 a month or $199.90 a year.
- **Sales calls:** Trackinsight Enterprise and ETF Insider Enterprise publish no price.

The free sites carry advertising and sponsored content beside the data — ETF.com prints press
releases under a fund's news, ETF Action runs sponsored model marketplaces, Trackinsight labels
sponsored articles. None of that changes a number, but it is the price of the free tier.

## Cards

- [ETF Action](https://stockmarketstack.com/tools/etf-action.md) — Daily US ETF flows, issuer league tables and look-through analytics, aimed at advisers.
- [ETF.com](https://stockmarketstack.com/tools/etf-com.md) — A free US ETF screener, flows tool and fund pages on FactSet data, with an AI assistant.
- [ETF Insider](https://stockmarketstack.com/tools/etf-insider.md) — Look-through overlap, concentration and correlation for a portfolio of US funds.
- [ETF Research Center](https://stockmarketstack.com/tools/etf-research-center.md) — Holdings-level ETF research — overlap, stock locator and fundamentals rolled up per fund.
- [ETFreplay](https://stockmarketstack.com/tools/etfreplay.md) — Ranks US ETFs by relative strength and backtests rotation and moving-average rules.
- [justETF](https://stockmarketstack.com/tools/justetf.md) — A screener and portfolio planner for European UCITS ETFs — no US listings, no API.
- [Trackinsight](https://stockmarketstack.com/tools/trackinsight.md) — A free global ETF screener — 15,875 funds across listing venues, with daily flows.

## Head to head

- [ETF Research Center vs ETF Insider: two funds, or the whole portfolio](https://stockmarketstack.com/compare/etf-research-center-vs-etf-insider.md)

## FAQ

### What is the best free ETF screener?

It depends on where the fund is listed. For US-listed funds, ETF.com's screener and flows tool cost nothing and need no account. For a universe that spans US, European and Asian listings, Trackinsight screens 15,875 funds free with a login. For UCITS funds bought through a European savings plan, justETF's free screener filters by domicile, distribution policy and broker availability, which no US tool does.

### How do I check the overlap between two ETFs?

ETF Research Center's Fund Overlap tool takes any two equity ETFs and returns overlap by weight, the shared-holdings count and the biggest differences; anonymous visitors see five rows, a free login shows the full list. For a whole portfolio rather than a pair, ETF Insider breaks every fund down to its holdings at once. Both are only as current as the holdings behind them, which can be months old.

### Is the expense ratio the real cost of owning an ETF?

No, it is the one cost printed on the label. The bid/ask spread is paid on every trade, and tracking difference — how far the fund actually trailed its index over a year — absorbs fees, withholding tax on dividends, securities-lending income and cash drag together. On 7 October 2026 Trackinsight showed SPY trailing the S&P 500 by roughly 10 to 14 basis points over a year and IVV by 3 to 4.

### Where can I research UCITS ETFs?

justETF covers European listings only and is built around the questions a European buyer asks — domicile, accumulating or distributing, savings-plan availability. Trackinsight covers UCITS funds alongside the rest of the world and adds French PEA eligibility and UK reporting status. ETF Research Center screens a UCITS universe too. ETF.com, ETF Action, ETF Insider and ETFreplay are US-listed only.

### Where can I see ETF fund flows?

Free, in three places. Trackinsight prints one-month and year-to-date flows on every fund and a daily global flows board. ETF.com's Fund Flows tool returns net flows for a fund, issuer or asset class over any date range. ETF Action publishes a daily flow report and issuer league tables, with the underlying data from 29 dollars a month.

### How current is the holdings data on ETF research sites?

Rarely as current as the price. Trackinsight's holdings for SPY were stamped 31 August 2026 when read on 7 October. ETF Insider updates from quarterly SEC filings, which arrive up to 60 days after quarter end. Issuers publish full holdings daily on their own sites, and that is the source to check before acting on an overlap figure.