Ten names hold 89% of the typical book.
Family offices above a threshold have to file what they hold in listed shares, every quarter, in public. Almost nobody reads them together. Here is the distribution: 40 offices, 22 quarters, nobody named.
The number that surprises people is not the size of these books. It is how few positions decide them, and how much of what one office owns the rest of them already own too.
| Lowest tenth | Lower quarter | Middle | Upper quarter | Highest tenth | |
|---|---|---|---|---|---|
| Listed names held | 3 | 7 | 16 | 48 | 118 |
| Money in the ten largest | 51% | 66% | 89% | 100% | 100% |
| Money in the few that carry the book | 80% | 81% | 82% | 88% | 95% |
| Turned over in a quarter | 0.0% | 0.6% | 3.2% | 12% | 27% |
| Names let go in a quarter | 0.0% | 0.0% | 1.6% | 10% | 19% |
| Already owned by the others | 0.2% | 1.1% | 4.1% | 8.7% | 15% |
| Held through options | 0.0% | 0.0% | 0.0% | 0.0% | 0.9% |
39 of 40 offices had filed by the deadline for that quarter. The rest are counted as late, not dropped.
Half of these books hold 16 listed names or fewer. A quarter hold 7 or fewer.
The middle office keeps 89% of the reported book in ten names. At the top quarter it is 100%.
Four fifths of the money sits in a handful of positions in every one of these books. The question is never how many names. It is which few.
Half of these positions are gone within 6 quarters. Positions still open are counted as unfinished, not as short.
1 office stopped filing part way through. It stays in every figure above. Records that quietly lose the ones who left are the reason most cohort numbers flatter.
Not a performance record. Listed shares held long are the only part of a book a filing covers — usually the smaller part.
Five readings, one at a time.
Do family offices have to file Form 13F?
Yes, above $100 million of listed securities. The threshold, the deadline, and what the filing leaves out.
Fewer names than anyone guesses.
How short a family office's listed book really is, and what the count cannot tell you.
The top ten is the book.
Where the money sits inside a short list, and the crowding nobody counts.
By the time the number is public, the quarter is gone.
What a quarter-end snapshot can tell you, what it hides, and why late filers stay in.
The filing is the smaller half.
Everything outside the listed sleeve, and why no return appears anywhere here.
Your own book has the same shape, and you already know which few positions decide it. The question is whether the number agrees with you.
Public filings only, and only the part of a book they cover: listed shares held long. No private holdings, no cash, no debt, no fees, no tax. Offices that stopped filing stay in every figure. Nobody here is named. The cohort is other firms' public quarterly filings, read as they stood on the day each one became public. It is not our clients, not their data, and not a performance record. Figures are computed from the filings themselves, as they stood on 2026-09-20. A record and an analysis, not investment, tax or legal advice; decisions rest with the family and its advisers.