Does copying 13F filings work? A revised historical simulation
Compare each manager with its own-window benchmark
| Investor | Execution window | Gross return | QQQ, same window |
|---|---|---|---|
| Stanley Druckenmiller | 2024-08-15 → 2026-08-17 | +179.5% | +55.5% |
| Cathie Wood | 2024-07-29 → 2026-08-17 | +161.8% | +59.0% |
| David Tepper | 2024-08-15 → 2026-08-17 | +107.1% | +55.5% |
| Philippe Laffont | 2024-08-15 → 2026-08-17 | +80.4% | +55.5% |
| Bill Ackman | 2024-05-16 → 2026-05-18 | +76.5% | +57.9% |
| Warren Buffett | 2024-08-15 → 2026-08-17 | +34.6% | +55.5% |
As of 2026-09-28, over 8 rebalances: Druckenmiller +179.5% vs QQQ +55.5%; Buffett +34.6% vs QQQ +55.5% (2024-08-15 to 2026-08-17). Wood +161.8% vs her own-window QQQ +59.0%; Tepper +107.1% vs QQQ +55.5%. Different managers can have different windows. These results do not establish future alpha.
Incomplete histories are excluded, with reasons retained under failures. The old same-day-close and option handling had defects; the figures here have been recomputed.
Download this page source and calculation snapshot · Open Compass research calculator
Method questions
Does this prove that copying will make money?
No. As of 2026-09-28, over 8 rebalances: Druckenmiller +179.5% vs QQQ +55.5%; Buffett +34.6% vs QQQ +55.5% (2024-08-15 to 2026-08-17). Wood +161.8% vs her own-window QQQ +59.0%; Tepper +107.1% vs QQQ +55.5%. Different managers can have different windows. These results do not establish future alpha.
Why use a later execution price?
A filing-day close can precede a post-market disclosure. The revised simulation waits until the next completed trading-session close. This remains a price assumption, not proof of an actual fill.
What is excluded?
Version 13f-next-session-v2 uses the first completed trading-session close after the filing date, excludes Put/Call and principal rows, and requires complete adjusted prices on matching dates and contiguous quarters. These are gross historical simulations before costs, taxes and slippage, not live returns. Current-universe selection and survivorship bias remain; original filings do not reconstruct all amendments or confidential disclosures.
Where can I inspect the data?
The dated JSON snapshot records each filing source, execution dates, price coverage and exclusions. 6 managers have complete histories; other attempts are listed under failures. Use each manager own-window benchmark.
SEC 13F FAQ · Create your own thesis and counterevidence record
Research only. Not a stock recommendation, live track record or return promise.