This page explains how IndexKite’s numbers are produced, once, in full, so every article can link here instead of repeating it.
Sources
The core sources are public data sets published by the U.S. Securities and Exchange Commission:
- Form N-CEN data sets: annual census filings. Used to identify index funds (the fund’s own “index fund” answer) and ETFs.
- Mutual Fund Prospectus Risk/Return Summary data sets: the fee tables from fund prospectuses, by share class.
- Form N-PORT data sets: fund portfolio holdings.
Other sources (fund prospectuses, the SEC’s Investor.gov, IRS publications) are linked where they’re used.
How we count
- A fund is an index fund if it says so in its most recent Form N-CEN filing.
- Funds are counted once per series, using the SEC series ID, so a fund with five share classes counts as one fund. Fee comparisons are done per share class, because that’s what an investor actually pays. Every table says which of the two it uses.
- Missing data is excluded, not counted as zero. Every percentage states how many funds or share classes it’s calculated on (“of the share classes that report an expense ratio…”, with the actual number).
- Names aren’t used to match funds. The same company can appear under several spellings, so matching is done by SEC identifiers.
- The data date is always stated: the quarter of the data set and the date it was checked.
These figures are my own calculations from SEC data. The SEC published the data; it didn’t draw the conclusions.
When our number differs from someone else’s
Counts from fund-industry groups or data vendors can differ because they define “index fund” differently, include or exclude ETFs and funds of funds, or count share classes instead of funds. When a well-known figure disagrees with ours, the article explains why and shows how the two reconcile.
Checking
Figures are calculated with scripts directly from the source files, and every number is checked against its source before an article is published.
Updates and corrections
Data-based articles are refreshed when the SEC publishes a new quarter, and the “data as of” line changes with them. Corrections are made promptly; significant ones are noted at the end of the article. Report errors to contact@indexkite.com.
Independence
No fund company, broker or advertiser reviews or approves content before publication.