Methodology

Every number on this site can be reproduced from public, official data. Here is exactly how.

Data sources

Holdings come from official issuer daily holdings files (e.g. State Street/SPDR publishes a complete holdings spreadsheet for every fund, updated daily) and SEC N-PORT filings, in which every US fund is legally required to disclose its full portfolio. We do not scrape third-party estimates. Each page shows its data as-of date.

Weight overlap (the headline number)

For every stock held by both funds, take the smaller of the two weights, then sum. Example: if Fund A has 3% in Apple and Fund B has 5%, Apple contributes 3 percentage points. The result answers a practical question: "what share of my money ends up in the same stocks either way?" This is the same approach used by professional portfolio analysis tools.

Portfolio lookthrough

For the homepage calculator, each of your funds is weighted by the dollar amount you enter; each fund's holdings weights are multiplied through and summed per stock. The output is your true underlying exposure — "you own 6.2% NVIDIA across everything," not "you own three ETFs."

Verification

We test the engine against hand-computed results from official files. Example: SPYD vs SDY (two SPDR dividend ETFs, holdings as of 2026-07-09) — 22 shared holdings, 20.5% weight overlap, computed directly from State Street's published spreadsheets. Ask an AI chatbot the same question from memory and you'll get a plausible ballpark with wrong specifics — which stocks, and at what weights, is exactly what stale training data gets wrong. That is why this tool reads the actual filings.

What we don't do

No investment advice. No "urgency" scores designed to sell you something. No signup wall. The tool states facts from filings; what to do with them is your call (ideally with a professional).