How to Read a 13F Filing (Fields, Timing, and Gotchas)
What a 13F filing is, who has to file one, the 45-day reporting lag, and the fields and gotchas that trip people up when reading institutional holdings.
TL;DR: A Form 13F is a quarterly SEC filing that discloses the long U.S. equity positions of institutional managers with at least $100M in qualifying assets. It is due 45 days after quarter-end, so it is always a backward-looking snapshot. It does not show shorts, cash, or most non-U.S. holdings. Read it as a lagged picture of conviction, not a live portfolio.
What is a 13F?
Form 13F is mandated by Section 13(f) of the Securities Exchange Act. Any institutional investment manager exercising discretion over $100 million or more in "13(f) securities" (mostly U.S.-listed equities and certain options) must file one every quarter, listing those positions.
The timing gotcha (read this first)
A 13F reflects holdings as of quarter-end, but managers have 45 days to file. So when a 13F hits SEC EDGAR, the underlying snapshot can already be six weeks old, and the manager may have changed the position since. This lag is the single most important thing to internalise: a 13F tells you what someone held, not necessarily what they hold now.
The fields you'll actually read
| Field | What it means |
|---|---|
| Issuer / name of security | the company held |
| CUSIP | the security's identifier (how you join to a ticker) |
| Value | reported market value of the position at quarter-end |
| Shares (or principal) | size of the holding |
| Investment discretion / type | sole vs. shared discretion; option call/put flags |
To compare across quarters you derive the change: new, added, reduced, exited, or held. That delta, not the raw snapshot, is where the signal lives.
The big gotchas
- No shorts. 13F is long-only disclosure. A fund could be net short a name you see listed long.
- No cash, no most non-U.S. holdings. It is not the whole portfolio.
- Options are reported as the underlying shares, which can overstate exposure.
- CUSIP-to-ticker mapping is on you. Identifiers change; corporate actions complicate it.
- Amendments happen. A manager can restate a filing after the fact.
How to pull 13F data programmatically
Reading one filing by hand is fine. Tracking 200+ managers across quarters, mapping CUSIPs, and computing changes is not, this is what an API is for. Arkolith ingests SEC EDGAR 13F-HR filings, resolves identifiers, and computes quarter-over-quarter changes, each datapoint sourced back to the original filing. Browse it on the funds directory or query it via the API and MCP server.
Frequently asked questions
How often are 13Fs filed?
Quarterly, due 45 days after each calendar quarter-end.
Who has to file a 13F?
Institutional managers with $100M+ in 13(f) securities under discretion.
Does a 13F show short positions?
No. It is long-only disclosure of U.S. equity (and some options) positions.
Arkolith turns raw 13F filings into clean, sourced, queryable data. Browse the funds or get a key to query them from your agent.