There's something a little thrilling about peeking at the portfolio of a famous investor. Four times a year, every large money manager in the US has to show the public what stocks they hold. Hedge funds, pension funds, the big asset managers, all of them.
It's one of the best free resources out there. It's also one of the easiest to misread. Here's how it works and how I use it.
What a 13F is
If an investment manager controls more than $100 million in US-listed stocks and some related securities, they have to file a Form 13F with the SEC every quarter.
The filing lists every position they hold at the end of the quarter: the company, the number of shares, and the value.
The deadline is 45 days after the quarter ends. So holdings on March 31st are due by mid-May.
The catch: it's old and it's partial
This is the part that gets skipped in most "copy the billionaires" videos.
It's a photo, not a video. A 13F shows what a fund held on one day. It doesn't show what they bought the day after, or what they sold in the middle of the quarter and bought back before the end.
It's up to 45 days late. By the time you see the filing, the fund could have sold the whole position. You're looking at last quarter's decisions.
It only shows some things. A 13F covers long positions in US-listed stocks, plus some options and convertibles. It does not show:
- short positions
- cash
- most bonds
- foreign stocks not listed in the US
- many other kinds of assets
So a fund that looks heavily invested in tech on its 13F could be fully hedged with shorts you'll never see. The 13F is one side of the story.
Some positions can be hidden for a while. Managers can ask the SEC to keep a position confidential, usually while they're still building it.
So why bother?
Because even with all that, 13Fs tell you things you can't get anywhere else.
Who owns a stock. On any company, you can see which big funds hold it and how much. A small company that suddenly shows up in the filings of several well-known value funds is interesting.
What changed. The useful signal usually isn't the holding itself, it's the change. A new position, a big add, or a full exit from one quarter to the next tells you where a manager's thinking moved.
How concentrated someone is. A fund with 400 positions owning a stock means little. A fund with 15 positions putting 10% of its money into one name means a lot more.
How I use it
When I look at a stock, I check the fund holders the same way I'd check the insider trades. I'm not looking for someone to copy. I'm asking: who else has done the homework on this, and did they recently add or cut?
When I look at a fund, I skip the giant index-heavy positions and go straight to the smaller, odd ones. Those are usually where the real conviction bets are.
And I always remind myself the filing is at least six weeks old.
How we show it on Nakag.ai
Our funds page lists a set of well-known 13F filers. Click into any fund to see what it held at the end of the last quarter. On each stock page, the "Insiders and funds" section shows which funds hold that company, right next to the insider and congressional trades.
Put together, those three sources give you a decent sense of who's interested in a stock. Insiders tell you what the people inside are doing, Congress gives you a public-interest view, and 13Fs show you where the big money sat last quarter.
Chris
Nakag.ai
This post is for learning, not investment advice. Do your own research before you buy or sell anything.