Learn · Last updated September 8, 2026
How Whale's Nest Sources and Verifies Its 13F Data
Every number on Whale's Nest comes from one place: institutional investment managers' Form 13F filings, published by the U.S. Securities and Exchange Commission on EDGAR. We parse the filings, compute what changed between quarters, and have a human review what we publish. This page explains each step, because "check us against the source" only means something if you know exactly what we do.
Where the data comes from
The SEC requires institutional managers with $100M+ in qualifying assets to file a Form 13F within 45 days of each quarter-end. These filings are public, free, and canonical — every 13F tracker, including us, is downstream of them. We ingest filings directly from SEC EDGAR, not from any third-party data vendor.
We track a curated set of 300+ prominent managers rather than all ~9,000 quarterly filers — the selection favors well-known, mostly lower-turnover investors whose filings carry real information despite the 45-day lag.
How filings are parsed
13F filings arrive in inconsistent formats (XML with varying namespaces, older SGML/HTML tables). Our parser normalizes them into one structure: issuer, CUSIP, share class, value, share count, and put/call flag per position. Options rows are kept separate from share positions — a put is never counted as a long holding.
Managers that file under multiple entities are aggregated so a firm's reported portfolio isn't split across siblings, and positions are keyed on CUSIP so the same security matches across quarters even when names differ between filings.
How changes are computed
The quarter-over-quarter comparison — new positions, exits, increases, trims — is computed from the filings themselves, keyed on CUSIP, using share counts, not market values, to distinguish real buying and selling from price movement. A position whose value fell while its share count held steady is not reported as a sale. (Why that distinction matters: how to read a 13F.)
How we verify
- Against the SEC's own extraction: our parsed holdings are checked against the SEC's published structured data for the same filings.
- Fail-visible, not fail-silent: filings our parser can't fully process are flagged rather than published partially.
- Human review: articles under the Whale's Nest Research byline are generated from frozen snapshots of our database, every figure is machine-checked against that snapshot before publication, and reviewed by a person. Data pages in the app come straight from the parsed filings.
What we don't do
- No "real-time" claims. 13F data is 45–135 days old by law. Anyone implying otherwise is overclaiming; the lag is stated on our pages.
- No completeness claims. A 13F omits shorts, cash, bonds, most foreign holdings and option details; so do we.
- No advice. We report what managers filed and what changed. Nothing on Whale's Nest is investment advice.
Corrections
If a number on Whale's Nest doesn't match the underlying filing on EDGAR, we want to know: the fix is re-parsing the filing, and it propagates everywhere the number appears. EDGAR is the arbiter in every case — we mean it when we say check us against the source.
FAQ
How quickly do new filings appear? Filings are synced from EDGAR daily; a new 13F typically appears within a day of publication, and followers of that manager are emailed when it does.
Do you use any data source other than SEC EDGAR? No. All holdings data is parsed from EDGAR filings directly. No third-party feeds, no scraped aggregates.
Why do your numbers sometimes differ from other trackers? Common causes, in order: sibling-entity aggregation (we sum a firm's filing entities; some trackers list them separately), put/call handling (we exclude options from long-position totals), and the pre/post-2023 value-units convention that some aggregators misapply.
Form 13F requirements and deadlines per the SEC's Form 13F FAQ. Nothing here is investment advice.
