Filings, funds, and the data behind them
Data readouts from 1.87M institutional positions across 1,824 filers, and guides to SEC filings, insider activity, and market data for AI agents. New articles daily.
Critical Third Parties: UK Cloud Rule Explained
A Critical Third Party is a provider whose service failure could threaten UK financial stability. The first UK designations are four cloud providers.
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13F Holdings API: Query Funds, Stocks, Quarters
A 13F holdings API turns SEC institutional ownership filings into resolved fund, stock, quarter, and point-in-time queries with filing provenance.
Insider Trading Data API: Query Form 4 Filings at Scale
What a good insider trading data API looks like: Form 4 mechanics, amendment handling, derivative separation, provenance, and code examples for agents.
How to Read SEC Filings: A Beginner's Map
SEC filings split into company reports and ownership disclosures. Learn which form answers which question, and where the who-owns-what data actually lives.
What Is a Prime Broker? The Plumbing Behind Hedge Funds
Prime brokers are the custody, financing, and stock-loan layer under every hedge fund. None of it shows up in a 13F. Here is how the plumbing actually works.
Hedge Fund Clone Portfolios: Sizing, Timing, Caveats
How to build a hedge fund clone portfolio from 13F filings: manager selection, three weighting schemes, the quarterly rebalance calendar, and the caveats that compound.
Sector Rotation Explained: What 13F Flows Really Show
Sector rotation is capital moving between sectors. Raw 13F net flows overstate it because price drift inflates every winner. Here is how to adjust for it.
Family Office 13F Rules: Why Some Investors Vanish
Some of the most famous investors file no 13F at all. What the family office exemption actually covers, what still gets disclosed, and where the record goes dark.
Institutional Ownership: How to Find Who Owns a Stock
Institutional ownership is the share of a company held by funds rather than individuals. What it means, why the biggest holders are usually index funds, and how to read it.
Activist Investor 13D Filings: How Stakes Surface
How activist stakes surface through Schedule 13D: the 5% trigger, Item 4 intent, the 2023 shift to five business days, and reading the amendment chain.
Measuring Portfolio Turnover From 13F Filings
How fast does a manager really trade? A practical method for estimating portfolio turnover from quarterly 13F snapshots, what high and low readings imply, and the caveats that bite.
Hedge Fund Concentration Explained: Reading a Top-10 Book
What top-10 weight and position counts reveal about a hedge fund's conviction, how to compute concentration from 13F holdings, and where the number misleads.
Can You Copy Hedge Fund Trades? The 45-Day Reality
Cloning hedge fund portfolios from 13F filings means trading on data at least 45 days stale. What survives the lag, what breaks, and how to cross-check with faster filings.
Who Owns Walmart (WMT)? Institutional Ownership Map
More than 1,000 institutions disclose Walmart positions in their 13F filings. Here is the real cap-table picture: the passive index core, the active money moving, and what 13F leaves out.
Agent-Native APIs Explained: What Makes an API Agent-Ready
Most data APIs were designed for a developer reading docs. Agents need discoverable tools, metered credits, and provenance on every datapoint.
Why LLMs Get Stock Data Wrong: A Failure Taxonomy
Training cutoffs, ticker collisions, merged share classes, and invented numbers: the four ways language models botch stock data, and what fixes each.
How AI Agents Cite Sources: Auditable AI Citations
Auditable agent answers need structured citations: accession-level source links, filing dates, and UI receipts. The schema and the enforcement rules.
Who Owns JPMorgan Chase (JPM)? Ownership Map
More than 1,100 institutions disclose JPMorgan Chase positions in their 13F filings. Here is the real cap-table picture: the passive index core, the active money moving, and what 13F leaves out.
API Keys for AI Agents: Scoping, Metering, Rotation
Agents leak, loop, and retry. How to scope, meter, and rotate API keys when the caller is an autonomous AI agent, and why a key must never live in a prompt.
Build a 13F Tracker with AI: Raw EDGAR vs a Clean API
An honest build-vs-buy tutorial: what parsing raw EDGAR 13F filings yourself really costs, versus pointing your AI agent at a clean, provenance-tracked API.
An AI Agent Stock Research Workflow That Cites Sources
A practical end-to-end workflow for agent-driven stock research: entity resolution, 13F ownership, Form 4 insider activity, and citations back to EDGAR.
Data Provenance for AI: The Anti-Hallucination Contract
Provenance means every number an agent states carries a link to its primary source. The contract, the response schema, and the enforcement rules.
Grounding LLM Responses: RAG, Tools, or Fine-Tuning?
RAG, tool calls, and fine-tuning solve different grounding problems. For financial numbers, only source-linked tool calls make the answer auditable.
Who Owns Costco (COST)? Institutional Ownership Map
673 institutions disclose Costco positions in their 13F filings. Here is the real cap-table picture: the passive index core, the active money moving, and what 13F leaves out.
What Is LLM Tool Calling? How It Actually Works
Tool calling is how an LLM stops guessing and starts querying. Here is the schema, call, result loop, and why it beats RAG for live structured data.
MCP vs Function Calling: Protocol vs Pattern Explained
Function calling wires tools into one app. MCP publishes them once for every host. How the two layers relate, and when each fits your agent stack.
ChatGPT Market Data: How to Connect Actions, MCP, and REST
ChatGPT has no market data built in. Here are the three connection paths that actually work: custom GPT actions, MCP connectors, and REST with a bearer key.
Institutional Ownership Percentage, Explained
What "X% institutionally owned" really measures, how 13F aggregation produces the number, and why different screeners disagree on the same stock.
Who Owns Coinbase (COIN)? Institutional Ownership Map
More than 360 institutions disclose Coinbase positions in their 13F filings. Here is the real cap-table picture: the passive index core, the active money moving, and what 13F leaves out.
What Is a Security Master Database? A Builder's Guide
Every serious data shop builds a security master: the reference layer that maps identifiers, issuers, and corporate actions. Here is why it never stays clean.
Share Classes Explained: GOOG vs GOOGL and Dual-Class Stock
GOOG and GOOGL are both Alphabet but not the same security. How dual-class structures, separate CUSIPs, and lazy ticker joins corrupt holdings data.
Corporate Actions Data: Why Your Position Deltas Lie
Splits, spin-offs, mergers, and re-listings silently corrupt 13F position-change analytics. The detection signatures that separate real trades from paperwork.
Survivorship Bias in Fund Data: Why Dead Funds Matter
Funds that close simply stop filing, vanish from current-holdings datasets, and quietly flatter every backtest built on the survivors. The mechanism and the fix.
What Is Point-in-Time Data? Look-Ahead Bias Explained
Point-in-time data preserves what was known when, not just what happened. Why backtests fail without it, how 13F amendments rewrite history, and what bitemporal storage fixes.
Who Owns Disney (DIS)? Institutional Ownership Map
630 institutions disclose Walt Disney positions in their 13F filings. Here is the real cap-table picture: the passive index core, the active money moving, and what 13F leaves out.
Entity Resolution in Financial Data: The Hard Problem
Two records, one company? Name variants, CIK vs LEI, and the manager-vs-fund split make entity resolution the quiet hard problem in financial data.
CUSIP vs ISIN vs FIGI vs Ticker: Which ID to Use
Every security carries at least four names. Here is how CUSIP, ISIN, FIGI, and tickers differ in scope, stability, and licensing, and when each breaks.
How to Track Insider Transactions With Form 4 Data
Form 4 puts every insider trade on the public record within two business days. How to filter for code P, weight buying clusters, and wire the feed into an API workflow.
Form 4 Derivative Table vs Non-Derivative: Table I and II
Form 4 splits insider activity into non-derivative Table I and derivative Table II. Naive trackers double-count option exercises and misread RSU vesting as conviction.
The 10 Percent Owner Rule Under SEC Law, Explained
Crossing 10% of a public company makes you a statutory insider: Form 3 and Form 4 deadlines, the 13D/G overlap, and short-swing profit liability, explained.
Who Owns Netflix (NFLX)? Institutional Ownership Map
More than 1,000 institutions disclose Netflix positions in their 13F filings. Here is the real cap-table picture: the passive index core, the active money moving, and what 13F leaves out.
What Is a Section 16 Officer? Insider Status Explained
Section 16 insider status turns on function, not title. The officer test, director and 10% owner rules, filing deadlines, and the edge cases that trip up real filers.
Form 3 vs Form 4 vs Form 5: The Difference Explained
Form 3 reports initial insider ownership, Form 4 reports trades within 2 business days, and Form 5 is the annual catch-up. How the Section 16 trilogy fits together.
Insider Buying vs Selling: Which Is the Stronger Signal?
Insiders sell for a hundred reasons but buy for one. Why purchases dominate the research, and how cluster logic separates signal from noise in Form 4 data.
What Is a 10b5-1 Plan? Scheduled Insider Trading Explained
Insiders pre-schedule trades through 10b5-1 plans. Here is how they work, what the 2023 cooling-off rules changed, and how much signal a planned sale really carries.
Form 4 Transaction Codes Explained: P, S, A, M, F, G, D, X
A one-letter code on every Form 4 row separates real insider conviction from payroll plumbing. P, S, A, M, F, G, D, and X decoded, with the traps to avoid.
Who Owns AMD (AMD)? Institutional Ownership Map
630 institutions disclose AMD positions in their 13F filings. Here is the real cap-table picture: the passive index core, the active money moving, and what 13F leaves out.
13F vs N-PORT: Two Fund Disclosures, Explained
A 13F shows a manager's quarterly US equity longs. N-PORT shows a registered fund's entire portfolio. Who files each, the lag, and which one to use.
SEC EDGAR API Guide: Fetching Filings Programmatically
How to pull SEC filings straight from EDGAR: the JSON endpoints, index files, and rate limits, plus the parsing traps that make raw EDGAR harder than it looks.
CIK Number Lookup: What a CIK Is and How to Use It
Every SEC filer has a CIK, the permanent EDGAR identifier. How the format works, how to run a lookup, and the traps when funds rename or change managers.
What Is an SEC Accession Number? EDGAR's Primary Key
The accession number is EDGAR's primary key: one unique ID per filing submission. Here is its exact format, how it maps to permanent URLs, and why provenance keys on it.
Who Owns Palantir (PLTR)? Institutional Ownership Map
More than 570 institutions disclose Palantir positions in their 13F filings. Here is the real cap-table picture: the passive index core, the active money moving, and what 13F leaves out.
13F Data Backtesting: Point-in-Time Discipline for Quants
Backtesting on 13F data fails quietly when holdings are joined to quarter-end dates instead of filing dates. The point-in-time rules that keep the research honest.
13F Total Value vs AUM: Why the Numbers Never Match
A 13F total is a long-only, US-listed snapshot, not assets under management. What the filing omits, what inflates it, and how to read the gap.
Who Owns Meta (META)? Institutional Ownership Map
770 institutions disclose Meta positions in their 13F filings. Here is the real cap-table picture: the passive index core, the active money moving, and what 13F leaves out.
Does 13F Show Short Positions? No, and That Matters
13F filings disclose long US equity positions only. Why short books are invisible, how that skews bullish readings, and where short data really lives.
The 13F Securities List: What Counts, What Never Shows
Only CUSIPs on the SEC’s official 13(f) list are reportable: US-listed equity, ETFs, ADRs, and listed options. Shorts, bonds, and foreign listings are invisible.
13F Confidential Treatment: How Funds Hide Positions
How institutional managers legally delay disclosing positions on Form 13F, how the SEC decides confidential treatment requests, and how hidden stakes surface.
13F Amendments Explained: Restatement vs New Holdings
A 13F/A either replaces the original filing or patches it. Why the two amendment types demand opposite handling, and how naive aggregators double-count quarters.
Who Has to File a 13F? The $100M Threshold Explained
The 13F obligation hinges on one test: $100 million in covered US equities under discretion. Here is who qualifies as an institutional manager and who escapes.
Who Owns Google (GOOGL)? Institutional Ownership Map
More than 800 institutions disclose Alphabet (Google) positions in their 13F filings. Here is the real cap-table picture: the passive index core, the active money moving, and what 13F leaves out.
How Accurate Is 13F Data? Seven Failure Modes to Know
A 13F is a legal disclosure, not a clean dataset. Seven specific ways raw filings mislead: option legs, amendments, identifier changes, misreported units, and more.
Who Owns Amazon (AMZN)? Institutional Ownership Map
More than 800 institutions disclose Amazon positions in their 13F filings. Here is the real cap-table picture: the passive index core, the active money moving, and what 13F leaves out.
13F Filing Deadlines in 2026: The Full Calendar
Every SEC 13F deadline for 2026, when filings actually land, and how to be ready the moment hedge fund holdings go public. Includes Form 4 and 13D timing.
Who Owns Tesla (TSLA)? Institutional Ownership Map
More than 670 institutions disclose Tesla in their 13F filings, about $151B in long value. The cap-table picture: the passive index core, the active money moving, and what 13F leaves out.
Where Insiders Are Cluster-Buying: June 2026 Form 4 Data
Companies where three or more insiders bought stock on the open market in the last 60 days, from SEC Form 4 filings: Ryan Specialty, Charter, S&P Global, and a run of small banks.
Who Owns Microsoft (MSFT)? Institutional Ownership Map
More than 800 institutions disclose Microsoft positions in their 13F filings. Here is the real cap-table picture: the passive index core, the active money moving, and what 13F leaves out.
The Biggest Hedge Fund Moves of Q1 2026, Decoded
In Q1 2026, 652 funds "bought" Versant and 404 "sold" CyberArk. Most of it was not trading. Here is what 13F position changes actually measure, with the real numbers.
Who Owns Apple (AAPL)? Institutional Ownership Map
More than 760 institutions disclose Apple positions in their 13F filings. Here is the real cap-table picture: the passive index core, the active money moving, and what 13F leaves out.
What Berkshire Hathaway Bought and Sold in Q1 2026
Berkshire tripled its Alphabet stake, opened a new Delta Air Lines position, and cut Chevron by 35%. A line-by-line readout of the Q1 2026 13F filing.
Who Owns NVIDIA (NVDA)? Institutional Ownership Map
More than 800 institutions disclose NVIDIA positions in their 13F filings. Here is the real cap-table picture: the passive index core, the active money moving, and what 13F leaves out.
The Most-Owned Stocks Among Hedge Funds in Q1 2026
We aggregated 1.87 million holdings from 1,824 institutional 13F filings for Q1 2026. Here are the stocks the most funds actually own, ranked by breadth of ownership.
How to Give Claude Access to SEC Filings
A practical tutorial: connect Claude to SEC filings over MCP in one command, the tools your agent gets, example prompts, and why provenance is the trust layer.
What Is Smart Money? A Measurable Definition
Smart money is measurable: 13F filers, corporate insiders, and activists who must disclose. Which filers count, which signals matter, and where the label breaks.
13F Options Explained: Puts, Calls, and the Notional Trap
13F filings report option positions at the value of the underlying shares, not the premium paid. How to read put and call legs without mistaking hedges for longs.
Can ChatGPT or Claude Access Live Market Data?
Out of the box, no, LLMs are frozen at their training cutoff. But you can give them live market data through tools. Here is how it actually works.
What Is a CUSIP? A Plain Guide for Holdings Data
A CUSIP is the 9-character ID that names a specific security in U.S. filings. Here is how it is built and why it matters when you work with holdings data.
13F vs 13D vs 13G vs Form 4: Who Owns What, Explained
Four SEC filings reveal who owns a stock, each with its own filer, threshold, and timing. Here is what 13F, 13D, 13G, and Form 4 actually tell you.
How to Stop Your AI from Hallucinating Numbers
LLMs confidently invent financial figures. The fix is not a better prompt, it is grounding the model in sourced data it can cite. Here is how.
The Best Market Data APIs for AI Agents in 2026
If you are wiring market and financial data into an AI agent, the right API depends on what you need. A practical, honest comparison for 2026.
MCP vs REST API: The Difference, and When to Use Each
MCP and REST often expose the same data, but one is built for your code and the other for an AI agent. Here is the practical difference and when each wins.
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.
How to Connect Market Data to Claude with MCP
A step-by-step guide to giving Claude (or any MCP client) live, sourced market data: get a key, add the MCP server, and start asking in plain language.
What Is an MCP Server? A Plain-English Guide for 2026
MCP (Model Context Protocol) is the open standard that lets AI agents call tools and pull live data. Here is what an MCP server is, in plain English.
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