Sarah Mitchell
Education Editor
Investment Education Editor at 13F Insight. Breaks down complex institutional data into actionable insights for individual investors.
A note from Sarah
Hi, I'm Sarah. I spent four years at Vanguard's Investor Education team, where my whole job was making 401(k) statements feel less like tax forms and more like something a person could actually understand.
I'm here at 13F Insight to do the same thing for institutional data. If you've ever read a headline like "Berkshire Bought Apple" and thought "okay but what does that actually mean for me," that's the gap I want to close.
I'll never assume you know what a CUSIP is. I'll always tell you why a number matters before I give you the number. And if a guide of mine ever leaves you more confused than you started, that's on me — let me know and I'll rewrite it.
Articles by Sarah Mitchell (818)
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When a Fund Buys a Whole Sector at Once: Macro Bets
A single new position can be a stock pick. But when a manager boosts three or four names in the same sector in one quarter, it usually signals a top-down macro view. Here is how to spot it.
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Why Founder Selling After an IPO Lockup Isn't a Red Flag
A founder selling millions of dollars of stock months after an IPO looks alarming, but it is usually routine diversification of concentrated pre-IPO equity. Here is how to check before you react.
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Why a Hot IPO's 13F Holders Are Mostly Market Makers
Open the holder list of a newly public, heavily traded stock and you will often see Jane Street, Citadel, and Susquehanna near the top — not long-only funds. Here is why, and what it does and doesn't tell you.
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When a Fund's 13F History Shows Assets Vanishing
A fund's reported assets can appear to collapse and then snap back a few quarters later. Usually that is not a real swing — it is a late or incomplete filing. Here is the tell.
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Why a Fund's 13F Value Can Fall Without Selling a Share
A fund's reported 13F value can rise or fall even when it never trades — price does the work. Here is how to tell mark-to-market moves from real buying and selling.
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What Is a 13F-NT? The Notice Filing Most Readers Skip
13F-NT is the notice filing institutional managers use when their qualifying assets are reported by another manager. It is a pointer, not a portfolio — and it is the single most-misread document in the 13F system.
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What Is a Schedule 13G? Passive 5% Stake Disclosures Explained
Schedule 13G is the SEC's disclosure for passive investors crossing the 5% ownership threshold. Index funds, insurance companies, and qualified institutional buyers file it instead of 13D when they have no intent to influence control.
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How to Read WhaleScore: 13F Filer Quality Composite
WhaleScore combines AUM, portfolio concentration, holdings count, and filer-type classification into a 0-100 composite. This explainer walks through each input, the score bands, and the five misreadings that send first-time users astray.
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Form 4 Insider Trading: What It Tells You About a Company
Form 4 reports corporate insider transactions within 2 business days of execution. This explainer covers transaction codes, the dual-class Table I trap, cluster buying patterns, and 10b5-1 plan sales — plus how to use Form 4 data on 13F Insight.
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What Is a 13D Filing? A Guide to Activist Investor Positions
Crossing 5% ownership of a public company triggers a Schedule 13D filing within 10 days. This explainer covers Item 4 intent, the 13D vs 13G distinction, amendment patterns, and how to read 13D filings on 13F Insight.
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How to Track Hedge Fund Portfolios Using 13F Data
13F filings are the only consistent window into hedge fund positioning. This explainer walks through the five-step workflow — picking funds, reading the baseline, tracking quarter-over-quarter changes, cross-referencing 13D/Form 4 — plus the gaps 13F cannot fill.
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13F Filing Season Guide: Deadlines and What to Watch
Four times a year, managers running over $100M in equity assets file Form 13F-HR with the SEC. This guide covers the 45-day rule, what's inside the filing, the 13F-HR vs 13F-NT distinction, and the reading order to use during filing season.
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Portfolio Concentration: When Fewer 13F Holdings Mean More
Whether a top 13F holding represents real conviction depends on portfolio concentration. This explainer covers top-N concentration, holdings count, and how to read them against real examples from Pershing Square, Berkshire Hathaway, and Vanguard Group.
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What Is AUM? The Three Numbers That Get Called the Same Thing
Assets under management means different things in different contexts: the firm's marketing number, the Form ADV regulatory number, and the 13F reported value are not the same. This explainer walks through what 13F AUM actually measures, and the five misreadings that get retail investors into trouble.
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Consensus Holdings: Reading Where Active Funds Agree
Consensus holdings are stocks owned by many institutional investors at the same time, with real portfolio weight. This explainer walks through how to compute them, how to use the 13F Insight consensus tool, and the three traps retail readers fall into.
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Dual-Class Shares and Insider Form 4 Filings
Many tech founders hold Class B shares with superior voting rights that don't appear in standard stock screeners. Understanding the dual-class structure helps investors read Form 4 Table II correctly and avoid underestimating an insider's real economic interest in their company.
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What Is a Rule 10b5-1 Trading Plan?
A Rule 10b5-1 trading plan lets corporate insiders sell shares on a prearranged schedule without violating insider trading rules. Understanding how these plans work helps investors correctly interpret insider Form 4 filings and separate mechanical selling from discretionary conviction shifts.
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Alt Asset Manager 13Fs: Blackstone, KKR, Apollo, Brookfield
Blackstone, KKR & Co, Apollo Global Management, Brookfield Asset Management, plus Carlyle Group and Ares Management anchor US-traded alternative asset manager 13F positioning. Multi-year emerging private credit growth, fee-related earnings transition, plus emerging emerging retail alternative access drive distinctive institutional patterns.
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Mid-Cap Pharma 13Fs: Jazz, Vertex, Royalty Pharma, Halozyme
Jazz Pharmaceuticals, Royalty Pharma, Halozyme Therapeutics, Catalyst Pharmaceuticals, plus Organon and Viatris anchor US-traded mid-cap pharma 13F positioning. Multi-year emerging royalty financing dynamics, ENHANZE drug delivery, plus emerging emerging biosimilar plus generic dynamics drive distinctive institutional patterns.
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Gene Therapy 13Fs: Vertex-CRISPR, BioMarin, Sarepta, Beam, Editas
Vertex-CRISPR Therapeutics Casgevy, BioMarin Roctavian, Sarepta Elevidys, plus Beam Therapeutics, Editas Medicine, Intellia Therapeutics, and Verve Therapeutics anchor US-traded gene therapy 13F positioning. Multi-year emerging AAV gene therapy adoption, CRISPR gene editing, plus emerging emerging in-vivo gene editing drive distinctive institutional patterns.