Buffett 13F Playbook

Generated from LEDGER.json by ledger-stats · as of 2026-08-17 local. Do not hand-edit; prose narrates, this block is the record.

Open positions

Who I Am (External Persona)

I am Warren Buffett via Berkshire Hathaway's 13F filings. I don't talk in this system. I'm mirrored: every quarter, when Berkshire files its 13F-HR with the SEC (45 days after quarter end), I diff that filing against the prior quarter and replicate the position changes here at scaled sizing.

This persona is not an internal voice. It is a signal source. What Berkshire adds, trims, and exits is the signal. My P&L tells you whether Buffett's quality-compounder-at-a-fair-price methodology is working in this regime.

Mission Statement (as copy-trader)

Mirror Berkshire Hathaway's quarterly 13F holdings in a $100K paper book. Scale each position change to our book based on Berkshire's own portfolio weighting — if Apple is 23% of Berkshire's 13F book and they add 2%, we allocate 2% of our $100K = $2,000.

Methodology (Buffett's, not ours)

1. Buy wonderful businesses at fair prices. Economic moat is the asset.
2. Hold forever if the thesis holds. Turnover is a tax.
3. Circle of competence. If you can't explain how it makes money, don't own it.
4. Float is free leverage. Insurance float funds equity positions.
5. Cash is a position. $300B+ in T-bills during stretched valuations is acceptable.
6. Concentration > diversification with conviction. Apple hit 50% of equity book.
7. Buybacks are a tell. When Buffett buys his own shares, he can't find better uses.

Entry Rules (as mirrored)

1. Quarterly 13F drops → diff vs prior quarter → NEW and INCREASED become BUYs.
2. NEW position: allocate newPct × $100K. INCREASED: allocate (newPct - prevPct) × $100K.
3. Trade price = close on the quarter-end date (e.g., Dec 31).
4. Skip sub-0.1% positions.
5. Must have OHLC data.

Exit Rules (as mirrored)

1. EXITED → full SELL at quarter-end close.
2. DECREASED → proportional trim (15% cut = 15% trim).
3. No independent stop-losses.

What I DON'T Do

• No derivatives, foreign holdings, private stakes.
• No mid-quarter trades.
• No second-guessing.
• No 13F-HR amendment chasing.

Known Tells

• Cash building 4+ quarters → Market is rich.
• New position >1% of portfolio → High conviction.
• Full exit of a long-held name → Something broke in the thesis.
• BRK.B buybacks accelerating → Berkshire is the best buy.

Data Source

• Primary: WhaleWisdom public holdings JSON (manager id 796)
• Fallback: --csv manual export
• SEC EDGAR CIK: 0001067983
• Filing cadence: ~45 days after each quarter end
• Import: deno task 13f-import --manager buffett

Current Regime Read

To be filled in after first import.