How to read a 13F step by step

1. Look at the quarter end, not the filing date

The 13F shows the portfolio on the last day of the quarter. It is filed up to 45 days later: what you see may be six weeks old.

Source: Search filings on EDGAR (SEC)

2. Compare with the previous quarter

A single portfolio says little. What matters is what came in, what went out and what gained or lost weight. Careful: if a stock rallied, its weight grows even if the manager bought nothing. That is why we show the “traded weight”, which separates buying from price moves.

3. Look at the weight, not just the name

A 0.2% position may be a test or a leftover; a 10% one is a bet. Concentrated portfolios say more than those with hundreds of stocks.

4. Separate stocks from options

Puts and calls are reported at the value of the underlying shares. A large put is not a bet against the stock as big as it looks.

Source: Frequently Asked Questions About Form 13F (SEC, Division of Investment Management)

5. Find the original filing on EDGAR

Every 13F is on EDGAR, the SEC's public archive, and can be opened without an account. You search by the firm's name or by its CIK, the number that identifies it; in the list of filings, the type is “13F-HR” (or “13F-HR/A” for an amendment). Each filing has two parts: the cover page, with the period, the portfolio total, the number of lines and the list of other entities included, and the “information table”, with one row per security. The date that matters for knowing when it became public is the acceptance date, which comes with a time. Each manager page here links to that document so any figure can be checked.

6. Add up share classes and repeated rows

The same company can appear on several rows. Sometimes because it has two share classes with different CUSIPs, such as Alphabet (GOOGL and GOOG) or Berkshire (classes A and B). Sometimes because the firm reports separately what each of its internal managers decides: a large manager's filing can carry five Apple rows. To know how much the company weighs in the portfolio you have to add them up. The reverse holds too: options on a stock go on rows of their own and are not added to the shares, because the reported value is that of the shares the option gives a right to, not what it cost.

7. Separate the effect of price

If a position went from 5% to 7% of the portfolio, it may be because the manager bought, because the stock rose more than the rest or because other things were sold. The number of shares settles it: if it did not change, the manager did nothing. Watch out for splits: after a 10-for-1 split, the count multiplies by ten without anyone buying. Changes here are calculated with split-adjusted counts, and two different figures are shown: the weight of the position and the “traded weight”, the part of the change that comes from buying or selling. A position listed as “trimmed” can weigh more than before if the stock rose a lot.

8. Look at several quarters, not one

A single quarter says little. A new position may be the start of a long purchase or a trial that is closed the following quarter. Looking at eight or twelve consecutive quarters shows something else: how long the manager holds positions, whether it buys gradually or all at once, whether it returns to companies it held before. Turnover shows too: the share of the portfolio that changes each quarter. For a manager turning over 60% a quarter, a 13F from 45 days ago describes a portfolio that probably no longer exists. For those with low turnover, the snapshot ages more slowly.

9. What no 13F will tell you

The filing does not say why the manager bought, at what price, or when within the quarter. It does not show short positions or hedges other than listed options, so a portfolio that looks heavily exposed to a sector may be offset by something that is not visible. It does not say whether the position is still open today. And it does not distinguish a strong conviction from an inherited position or one that is being sold down. It is a record of holdings at a date, filed with a delay. It is useful for researching what managers hold and how that changed; it is not enough to know what they think or what they will do.

10. A ten-minute walk-through

With a 13F open, this order is enough for a first read. First, the cover page: the period, the acceptance date, the total and the number of lines. Second, the ten largest positions and their combined weight: they show how concentrated the portfolio is. Third, what changed against the previous quarter, looking at shares rather than values: new, closed, increased and trimmed positions. Fourth, the options, separately. Fifth, whether there are amendments or whether another entity in the group reports part of the portfolio. That already tells you what the firm holds, what it did and which parts of the document cannot be read without more context. On the page for each quarter of a well-known investor that walk-through is done: the full table, the change in each line and the positions it closed.