TradeStar Insider · How-to

Fund position changes from SEC 13F filings

This explains how to ask an AI assistant (or the REST API) what large institutional managers changed in their holdings quarter over quarter — the positions they opened, added to, trimmed, or exited — with every figure linked to the source SEC filing.

What this signal is worth — read this first. A 13F is a snapshot of a manager's long US-equity positions as of quarter-end, filed up to ~45 days later. By the time you read it, it is public, widely covered, and up to a quarter and a half old. There are no transaction dates, no prices, and no short positions. So treat this as a convenience and completeness product — a clean, filing-linked way to see who changed what — not a trading edge. Anyone selling 13F deltas as alpha is selling you stale public data.

What you get

The product is the quarter-over-quarter delta, not the raw snapshot. Each record is one position change for one filer:

new_position — held this quarter, not last.
added / trimmed — share count moved ≥25% versus the prior quarter.
exited — held last quarter, gone this quarter.
no_prior_quarter — the filer's first filing on record, so there is nothing to diff. This is an explicit state, not silently reported as "everything is new."

Every record carries, as first-class fields, the as_of_quarter_end date, the filed_date, and the lag_days between them — so the staleness is on the record, never hidden in a footnote. Values (value_usd) are in whole US dollars. Options positions (puts/calls) are excluded; this is about share ownership.

No tickers, on purpose. 13F identifies securities by CUSIP, and there is no authoritative free source mapping CUSIP to a ticker. Rather than guess — a wrong ticker is worse than none — every record returns the cusip and the issuer_name exactly as they appear in the filing, and ticker is always null. If you need the ticker, resolve the CUSIP against a source you trust.

Which filers — the universe

The feed covers the fifty largest 13F filers by reported value as of the latest quarter (2026-06-30), re-ranked quarterly. It is not a curated "smart money" list and makes no claim to be one.

Ranked by reported value — read the head accordingly. Because the universe is ordered by dollar value on file, its head is the biggest asset managers — BlackRock, Vanguard, State Street, Fidelity and the like — whose quarter-over-quarter changes largely reflect index rebalancing, not conviction. This feed reports what was filed, not what it means: it does not tag any manager as active or passive, because that is inference. Same discipline as the 8-K tool — the filing is the fact; the interpretation is yours.

Coverage is tracked per SEC CIK, not per brand name. When a manager's 13F moves to a new CIK, the quarterly re-rank picks up the current entity; historical rows stay attached to the CIK that filed them. So a single brand can appear as more than one entry, and a retired CIK keeps the history it filed.

Step 1 — Connect the MCP server

In the Claude Code CLI, one line connects the live server:

claude mcp add --transport http insider-signals https://mcp.tradestarinsider.com/mcp

Any MCP client that supports remote Streamable HTTP servers works the same way; point it at https://mcp.tradestarinsider.com/mcp. No API key, no OAuth. The server is per-IP rate limited.

Step 2 — Ask in plain language

Once connected, ask the assistant directly. Examples:

"What did Berkshire Hathaway change in its latest 13F?"
"Show new institutional positions over $100M in the latest quarter."
"Which funds exited positions last quarter? Link the filings."

The assistant calls the fund_position_changes tool and returns the parsed change rows with their sec.gov links.

The tool it calls

fund_position_changes — quarter-over-quarter 13F changes. Optional filters: filer (fund name substring or CIK), change_type (new_position / added / trimmed / exited / no_prior_quarter), min_value_usd, limit.

How to trust the answer

Every change carries a filing_url pointing to the filing index on sec.gov. To verify any number, open that link and read the 13F information table directly — the CUSIP, issuer, share count, and value are on the filing itself. A delta (added/trimmed/exited) is the arithmetic difference of two consecutive quarterly filings for the same filer; both are linked. If a figure has no filing link, it is not in this feed — it is dropped, not guessed.

Prefer the REST API? The same data is available as JSON under an OpenAPI 3.0.2 contract at api.tradestarinsider.com/v1/openapi.json (operation fundPositionChanges, path /v1/fund/changes).

Information, not investment advice. Data from SEC EDGAR Form 13F-HR. A 13F is a ~45-day-old, long-only, US-equity snapshot; the changes derived from it are historical and public. See also: checking insider purchases with an AI assistant · verifying a financial claim against a filing.