Updated May 13, 2026 · 636 articles
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Educational guides about 13F filings, insider trading, institutional investing, and how to track smart money moves.
Why a $50B Endowment Shows Only $2B on Form 13F
University endowments routinely manage tens of billions of dollars, yet their Form 13F filings often disclose under 5% of that figure. The reason is structural: Form 13F only captures one specific slice of an investment book.
Sarah MitchellWhy Insurer 13F Tech Concentration Differs From Hedge Funds
When you see Legal & General Group reporting NVDA at 7.23% of its US 13F book, the instinct is to read it as a conviction tilt. The reality is much closer to a cap-weighted index sleeve. This guide explains why insurer 13F concentration looks high but isn't.
Sarah MitchellBroker-Dealer 13F vs Active Manager 13F: How to Tell Them Apart
Reading a 13F filing as a list of conviction trades works only when the filer is an active manager. For broker-dealers, custodians, and platform RIAs, the same document is a customer-account aggregate. This guide shows how to tell them apart.
Sarah MitchellReading 10b5-1 Plan Footnotes on Form 4 Filings
When a CEO sells stock, the question is rarely 'how much' — it is 'is this discretionary or pre-arranged?' This guide walks through how to read the Rule 10b5-1 plan footnote on a Form 4 and what it actually changes about the signal.
Sarah MitchellReading the 13F Tail: Why Top-500 Isn't the Full Portfolio
Most 13F analytics platforms display the top-500 positions per filer. The tail beyond position 500 is where new themes, small-cap conviction, and quiet rotations show up before they reach the headline holdings list.
Sarah MitchellETF Lines in 13F Filings: Client Wrap vs Active Bet
When a 13F filer reports SPY, IVV, or VOO in their top 10, it can be a programmatic wealth-channel client wrap — or a deliberate active bet. This guide shows how to tell the difference.
Sarah MitchellReading 13F Position Changes: Share Count vs Dollar Value
A 13F position can show a 50% dollar-value increase from share buying, from price appreciation, or both. This guide explains how to separate the two — and why share-count change is the cleaner signal for institutional conviction.
Sarah MitchellReading 13F Cluster Trades: When Two Managers Buy the Same Name
When two or more top-tier active managers build a meaningful position in the same name in the same quarter, the institutional read is different from any single filing. This guide explains how to read a cluster signal — and when to ignore one.
Sarah MitchellCUSIP Basics: The 9-Character Security ID for 13F Readers
CUSIP is the 9-character identifier that anchors every 13F filing line, every 13D filing, and every Form 4 transaction. Tickers can change, company names can rename, but a CUSIP stays put. Here's how the format works, why mixed-case CUSIPs matter, and what to watch for when joining datasets.
Sarah Mitchell13F-HR/A Amendments: What They Fix and What They Signal
A 13F-HR/A is an amendment to a previously-filed Form 13F-HR. Amendments are common, mostly mundane, and occasionally tell you something the original filing missed. Here's how to read one and decide whether the underlying position change is material.
Sarah MitchellReading 13F Voting Authority Columns: Sole, Shared, None
Every Form 13F-HR line item carries three voting authority columns: sole, shared, and none. The sum equals the position's share count, but the split tells you whether you're looking at an investment manager, a custodian, or a sub-advised pool. Here's how to read each column and what they imply about who actually controls the vote.
Sarah MitchellMarket-Maker 13F Holdings: Why They Aren't Investment Conviction
Susquehanna, Jane Street, Citadel, Wolverine, Optiver, and similar names show up at the top of many 13F holder lists. Their declared positions are large, frequent, and not what they look like. Treating market-maker inventory as investment conviction is the most common 13F-reading error in retail research.
Sarah MitchellSequential 13G Filings: Real Move or Reporting-Entity Transfer?
Reading institutional ownership well means knowing why a 13G/A filing changed. Sometimes the stake actually moved. Sometimes it's the same shares moving between two reporting entities under the same parent. Here's how to tell the difference using the same SEC filings everyone else looks at.
Sarah MitchellSchedule 13G/A Exit Filings: What They Reveal to Investors
Schedule 13G/A amendments marked as exits aren't bureaucratic housekeeping — they're often the cleanest read available on when a large strategic or institutional holder gives up on a position. Here's how to find them and what they actually mean.
Sarah MitchellHow to Spot a 10b5-1 Plan on Form 4: Pattern Recognition Guide
Not every CEO selling stock is bearish. Most executive sales today run through Rule 10b5-1 plans — pre-scheduled trading schedules that look identical to discretionary trades on the surface. Here's how to tell them apart from the Form 4 data alone.
Sarah MitchellRIA Aggregator 13Fs vs Active Manager 13Fs: A Reader's Guide
Two 13F filings can have the same headline AUM but tell completely different stories. RIA aggregator filings reflect pooled client allocations; active manager filings reflect a portfolio manager's view. Knowing which is which keeps you from over-reading either.
Sarah Mitchell13F-NT vs 13F-HR: What Notice Filings Actually Mean
Form 13F-NT is the notice filing institutional managers use when their holdings are reported in someone else's 13F-HR — or when they're invoking confidential treatment delays. Here's how to read each case without guessing.
Sarah MitchellForm 144 vs Form 4: What Each Filing Actually Tells You
Form 144 is filed before an affiliate's planned sale; Form 4 is filed after the transaction settles. Reading the gap between them is one of the cleanest insider-sale signals available — once you know how to look.
Sarah MitchellMulti-Class Shares: Why Form 4 Table I Misses Half the Story
Form 4 Table I is the headline number readers anchor on, but for any founder-led or dual-class company it only shows part of the picture. This guide explains where the rest of insider ownership lives, how to find it, and the most common multi-class reporting mistakes.
Sarah MitchellHow to Read Rule 10b5-1 Plan Signatures in Form 4 Filings
When a CEO files a Form 4 reporting a sale, the most important question is not how much was sold but whether the broker chose the timing. This guide shows you the data signatures that distinguish Rule 10b5-1 plan trades from discretionary view-driven sales.
Sarah Mitchell