If You Had $10,000, How Would a Fund Manager Invest It?

Three of the most successful disclosed books in our cloneability study, mapped onto a hypothetical $10,000. What professional position sizing actually looks like, what following each book really earned, and how to run this study yourself.

Here is a question worth sitting with: if a professional fund manager were handed your $10,000, what would the account actually look like? Not in spirit. Literally. How many stocks, at what sizes, and with how much riding on the biggest idea?

You do not have to guess. Four times a year, every large investment manager in the US discloses its stock holdings to the SEC. We loaded six years of those filings into Moneyta and replayed 312 of the largest managers' books the only way a regular person could actually follow them: buy the disclosed book the day after it becomes public, hold until the next filing, repeat. Most books were not worth copying at that delay. The typical one lagged the S&P 500 by about 1.9% a year, and only 52 of the 312 came out ahead at all.

This post walks through three books from that minority. Not because you should copy them. Because seeing how a real professional sizes real positions teaches more about portfolio construction than any listicle of hot stocks, and because the numbers that follow are checkable, on pages you can open without an account.

Book one: Berkshire Hathaway, the concentrated classic

Start with the most famous investor alive. As of its latest filing, Berkshire Hathaway's disclosed US stock book holds just 11 positions. Eleven. The whole thing is worth about $165 billion, and the top six names are 96% of it.

Map those disclosed weights onto a hypothetical $10,000 and the account looks like this: about $3,510 in Apple, $1,850 in Coca-Cola, $1,520 in Bank of America, $1,060 in Chevron, $950 in Alphabet, $650 in Moody's, and roughly $460 spread across the remaining five names.

Sit with the first line. One stock is a third of the account. Most retail investors would call that reckless, and most professionals would call it conviction. The lesson is not that you should put 35% into Apple. It is that professionals size positions by how much they believe, not by dividing evenly, and they hold shockingly few names for the size of their conviction.

Does following it work? Our replay says: barely, and honestly. Buying Berkshire's disclosed book the day after each filing since 2020 and holding to the next one earned 19.1% a year, against 18.3% for the S&P 500 over the same windows. An edge of 0.8% a year, with a worst drawdown of 12%. Even the greatest allocator of his generation, followed at the legal disclosure delay, beats the index by less than one point a year.

Book two: Sanders Capital, the quiet compounder

You have probably never heard of Sanders Capital, which is rather the point. It is a value manager running about $70 billion across 28 disclosed positions, and in our study its book was one of the strongest of the entire 500: following it at the filing lag earned 22.7% a year over four years, about 7.4% a year ahead of the index.

The same $10,000 mapped onto its weights: about $1,360 in Taiwan Semiconductor, $1,180 in Alphabet, $890 in Amazon, $870 in Meta, $720 in Seagate, $660 in Microsoft, and the remaining $4,320 across 22 more names, each between roughly 1% and 6% of the book.

Notice the shape difference. Berkshire is 11 names with a giant anchor. Sanders is 28 names with the biggest at 13.6%. Both are professionals; they simply price conviction differently. What neither book contains is 150 tiny positions, and that is the second lesson: diversification in professional hands is a few dozen researched names, not a little bit of everything.

Book three: Tiger Global, the growth bet

Tiger Global runs a concentrated growth book: 20 disclosed positions, heavy in the AI supply chain. The hypothetical $10,000 here: about $1,930 in Alphabet, $1,320 in Nvidia, $1,320 in Amazon, $1,190 in Taiwan Semiconductor, $1,120 in Meta, $700 in Broadcom, $580 in Microsoft, $530 in Lam Research, and roughly $1,310 across the remaining twelve.

Following this book at the lag earned 27.9% a year in our replay, about 8% a year ahead of the index, over a shorter scored window of 14 quarters at 90% priced coverage. The caveat matters more here than anywhere: a growth book that beat the index through an AI bull market is exactly the kind of result that flatters a backward look. The same concentration cuts both ways when the theme turns.

What the three books teach about your $10,000

• Professionals concentrate. Eleven to twenty-eight positions, not two hundred. Every one of these books would fail a robo-advisor's diversification screen, on purpose.
• Position size is an opinion. The biggest name in each book is 14% to 35% of it. Equal weighting is what you do when you have no view.
• The overlap is not an accident. Alphabet, Amazon, Meta and TSMC appear in two or three of the books at once. When independent professional books agree, that co-occurrence is information. When they disagree, that is information too.
• Even great books barely survive the lag. The median large manager lost to the index at the 45-day delay. These three are the exception, measured after the fact. That is the honest base rate a follower starts from.

How to run this study yourself in Moneyta

Everything above came out of screens you can open right now, without an account. Start at the fund manager directory: 500 of the largest books, searchable, each showing its top holdings and what changed last quarter. Open any manager and the page answers the question that matters before you borrow a single idea: was this book ever worth following at the delay, or does it just have a famous name?

Members get the rest of the process. The full book instead of the top ten. Quarter-over-quarter flows that show what a manager actually did, not just what it holds. The conviction screen that flags names where company insiders and large institutions moved the same direction in the same quarter. And the evidence pages, where every signal we surface carries its full historical base rate, including the times it failed.

One last honesty note, because it is the house rule. Nothing here says buy Apple or copy Sanders Capital. A disclosed book is a photograph taken 45 days ago; it says what a professional owned, not what you should own. What it does teach, better than anything else public markets offer for free, is how professionals actually structure money when it is theirs to lose. Learn the shape. The stocks are your call.