Thirteen F Superinvestor Coattail
In plain terms
When a small set of top-tier hedge fund managers (Buffett, Ackman, etc.) reveal a brand-new position on their quarterly 13F filing, the stock tends to drift up over the next 2-6 months as other investors copy the trade.
How it works
Practitioner 13F coattail, intentionally distinct from Cohen-Polk-Silli's construct. CPS define a manager's best idea as the EXISTING position with the largest active weight (portfolio weight minus benchmark weight) across all active managers; that max-tilt basket earns the paper's documented abnormal return, and the faithful CPS spec is implemented by the related family smart_money_best_ideas. This family instead rides brand-NEW 13F positions opened by a curated 21-firm superinvestor list (Berkshire/Pershing/Tiger/etc.), entering LONG after the 45-day filing lag. Closest academic support for post-disclosure copying: Martin-Puthenpurackal (2008) show a Berkshire-mimicking portfolio formed after public disclosure still earns significantly positive abnormal returns; Verbeek-Wang (2013) show copycat funds free-riding on disclosed holdings perform comparably to their targets.
Live results
54 times picked on its own · 130 times inside a blend (102 beat the stock) · updated 2026-06-06Data dependencies
- Daily prices
Adjusted-close OHLCV for every US-listed ticker; primary price feed.
- Investor holdings
A data feed this strategy reads, refreshed on its normal schedule.
- Investor filings
A data feed this strategy reads, refreshed on its normal schedule.
- Tracked investors
A data feed this strategy reads, refreshed on its normal schedule.
Expected edge
- Reported return
- Significant positive post-disclosure abnormal return for a Berkshire-clone portfolio (Martin-Puthenpurackal 2008); CPS's ~3-4%/yr max-active-weight figure is not applicable to this new-add coattail.
- Tested over
- Entry at quarter-end + 45-day filing lag; 60/90/180 trading-day holds (implementation grid; copycat literature studies post-disclosure horizons of months to quarters).
Qualitative: significantly positive post-disclosure abnormal returns for copycat portfolios (Martin-Puthenpurackal 2008 Berkshire clone). The previously listed ~3-4%/yr belongs to Cohen-Polk-Silli's max-active-weight best-ideas basket, a different construct, and must not be attributed to this signal.
Example tickers where this is likely to fire
Illustrative only, the signal fires based on the live data, not a fixed list.
Related families
When both 'how many funds bought the stock' AND 'how much they bought' jump together to top-20% of the stock's history in the same quarter, institutions are accumulating aggressively. Go long for 2-9 months.
Most fund managers add little value across their full book — but their TOP overweight (highest-conviction name) outperforms by 4-9%/yr. Clone those.
Explore Thirteen F Superinvestor Coattail on alphactor.ai
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