Method and Data
Every number comes from public filings with the US Securities and Exchange Commission (SEC), compiled by program; every original filing is linked so you can check the figures yourself.
What This Site Does
We take the quarterly 13F filings of a group of value investors (the “value giants”, or simply “giants”) and read them together: which companies they share, which way they moved this quarter, and how that changes over the years. The focus is on the giants as a whole, not on following one person’s individual trades.
What a 13F Is
- Under Section 13(f) of the US Securities Exchange Act, an institutional investment manager with investment discretion over $100 million or more in “13(f) securities” must file Form 13F with the SEC within 45 days after each quarter ends; a deadline on a weekend or holiday moves to the next business day.
- The filing lists long positions on the last day of the quarter: company, class, number of shares and value. 13(f) securities are mainly stocks listed on US exchanges (including ADRs of foreign companies listed in the US), closed-end funds and ETFs, plus some convertible bonds, options and warrants.
- Not shown: short positions, cash, ordinary bonds, shares that trade only on foreign exchanges (for example only in Hong Kong or Tokyo), open-end mutual funds, private companies, and when or at what price anything was bought or sold during the quarter.
- A manager can ask the SEC to keep some holdings confidential for up to a year; those positions appear later in an amendment, or never.
- Official sources: SEC, Frequently Asked Questions About Form 13F; 17 CFR 240.13f-1.
How the Giants Are Chosen
- In one sentence: investors with a public record of a value or quality approach, who file continuously, hold mainly stocks and show conviction.
- Four rules checked with numbers: filings in each of the last 8 quarters, at least $100 million in stocks, options under half of the filing, and no more than 150 holdings with the top 10 making up at least 40%; plus a judgement on investment style.
- The roster is recomputed every quarter with the same rules, at most 60 giants and never padded. Full rules and the verdict on all 84 candidates: How giants are chosen.
How Each Number Is Calculated
| Number | How | Estimate? |
|---|---|---|
| Weight | the company’s quarter-end value ÷ the giant’s total quarter-end stock value (options excluded) | No |
| Giants holding | number of giants holding it that quarter; share classes of one company count once | No |
| Composite weight | sum of each giant’s weight in the company ÷ number of giants counted that quarter (one vote each) | No |
| Quarter-end price | 13F quarter-end value ÷ shares, roughly the closing price; the median when several giants hold it | No |
| Quarter-start price | the previous quarter-end price (split-adjusted) | No |
| Est. trade price | (start price + end price) ÷ 2 | Yes |
| Est. trade value | change in shares × est. trade price | Yes |
| Est. average cost | shares added each quarter × est. trade price, weighted; trims leave the cost unchanged | Yes |
| vs cost | quarter-end price ÷ est. average cost − 1 (dividends excluded) | Yes |
| Position shift | change in shares × quarter-end price ÷ the giant’s whole portfolio (percentage points) | No |
| Net buyers | giants whose estimated buying exceeded their selling ÷ giants counted | Yes |
| Net deployment | estimated net buying this quarter ÷ last quarter’s portfolio; the average is taken over all giants | Yes |
| Turnover | the smaller of buying and selling ÷ the average portfolio | Yes |
| Top-10 concentration | combined weight of the 10 largest holdings | No |
| Overlap | for each company, the smaller of the giant’s weight and the composite weight, summed | No |
Plain-language definitions: Glossary.
Why Only Quarter-End Prices
- Daily prices have to be licensed from data vendors; a 13F already contains quarter-end values and share counts, and dividing one by the other gives the quarter-end price.
- The benefit: no licensing issues, and every number can be traced back to an SEC filing and checked by any reader.
- The cost: no live or daily prices and no intra-quarter highs or lows. “Now” always means the latest quarter-end price, and the date is shown.
- A 13F says only that something was bought during the quarter, not when or at what price, so the average of the start and end prices is used as an estimate. When the price swings a lot within the quarter, the estimate can be far off. Example: start 100, end 120, so the estimated trade price is 110; if the giant actually bought when the price dipped to 80, the real cost is much lower.
- When one end is missing, only the other is used: in the quarter of a sale, if no giant still holds the stock there is no end price, so the start price is used; in the quarter of a purchase, if no giant held the stock the quarter before there is no start price, so the end price is used. For the case studies in “Wins and Losses of the Giants”, such prices are filled in or checked against other firms’ 13F filings.
Data Quality
- Units: until January 3, 2023, values were reported in thousands of dollars, and in dollars after that; some filers used the wrong unit. The program cross-checks each filer’s totals and prices across neighbouring quarters and drops a filing it cannot resolve.
- Amendments (13F-HR/A): an amendment that adds new holdings is merged into the original; a full restatement replaces it; a partial restatement is merged line by line.
- Stock splits: detected from jumps in share counts, matching changes across several giants and the price change, and applied only when confirmed; unconfirmed positions are left out of return statistics.
- Changed security codes: a name change, merger or exchange can change a security’s code; two codes are linked only when the same holders hold exactly the same number of shares.
- Share classes: for example Alphabet’s A and C shares, or Berkshire’s A and B shares, are combined into one company; switching class is not a trade.
- Plain-text filings, 1999–2013: before Q2 2013 the holdings tables were plain text and are parsed line by line; about 74% of these filings add up to the total on their own cover page, and most mismatches come from errors on the cover page itself or from securities that are not 13(f) securities.
- When in doubt, leave it out: positions with an unconfirmed split or a possible code change are kept out of return statistics and listed for manual review.
When It Is Updated
- After each quarter’s filing deadline; while the latest quarter is still within its filing window, overall figures are marked preliminary.
- Giants file at different times, so a quarter’s numbers can change with late filings or amendments.
Check It Yourself
Every giant’s page links to the original SEC filing for each quarter. Quarter-end price = value ÷ shares in the filing, so you can compare directly.
Limits
- Survivorship bias: the roster is chosen today; managers who closed early, or who are no longer seen as value investors, are missing, and this matters more the further back you go.
- Delay: a 13F can arrive up to 45 days after the quarter ends; by the time you see it, the giant may already have changed the position.
- Estimates: trade prices, trade values, costs and returns are estimates.
- Not the whole picture: a 13F shows only long positions in US-listed stocks.
See also: Disclaimer & data notice, Privacy.