In one sentence: Phil and Danielle close their checklist series by explaining where the checklist comes from (a catalogue of mistakes), why inversion is the hardest part, and how to tell a real mistake from a pass that later looked wrong, using Buffett's baseball strike-zone story and two skipped Chinese stocks as examples.
Key ideas
- The checklist is a list of mistakes. Phil built it by reading decades of Buffett's letters and noting each mistake Buffett described (often only implied), then added his own errors and ideas from Mohnish Pabrai and Bill Ackman. Phil says it has roughly 70–80 points. [05:00–10:00]
- Stay well inside the checklist. Ackman came back to his own checklist after drifting to its edges. Near the edge it is easy to talk yourself into knowing more than you do. [06:00–08:00]
- Inversion is the hardest step. Analysts get so invested after 200 hours of work that they can't tear their own idea apart. Phil does the pushback for his team and doesn't let anyone buy for their own fund until the idea is fully accepted or rejected, to keep confirmation bias (and front-running) out. [07:00–10:00]
- Mistakes of omission. Phil's recent "mistakes" are things he didn't buy. He sent an analyst to research BYD, Alibaba and JD.com. Regulation and shareholder-rights issues in China kept him out, and some of the stocks rose 200–500%. [10:00–12:00]
- A pass can be the right decision. If you decided rationally on the information you had, it isn't a mistake, even if the stock rose (Danielle cites Annie Duke, Thinking in Bets; her own Lululemon pass is the same case). Regret is an emotional response, not an error. A fair lesson is to ask what you'd have had to know, and whether the inputs have changed (China's rules did). [12:00–16:30]
- The strike zone. Buffett's story: Ted Williams mapped the strike zone into baseball-sized cells and found where he hit best. Investors don't have to swing at every pitch, and their hittable zone is much smaller than Buffett's. Find the pitches you can hit: business you understand, a big moat, management you trust, a sale price. [16:30–19:30]
- Where to start finding your zone. What you're passionate about, talented at and spend money on are clues to where you already swing. [18:30–19:30]
- Don't clone a guru's trade. Danielle skipped BYD even though Munger was excited, partly because she couldn't tell what a reasonable price floor was. Munger's buy price is unknown and far lower than the market, so his margin of safety isn't yours, and he won't phone you when he sells. [20:00–23:00]
- Can't understand it, can't value it. If you aren't sure of the business you can't put a trustworthy price on it. Owning something you don't understand leaves you unable to buy more when it falls. [22:00–24:30]
- Check what a filing aggregator really shows. A "guru bought at $X" data point can reflect warrants or an earlier purchase. Phil cites Buffett's Bank of America warrants (bought for $5 a share via a loan), not an open-market buy at $30. [24:00–26:00]
- Value Line and similar services must keep finding "bargains" to sell subscriptions, so be wary of their "on sale" lists. This is Phil's opinion. [26:00–27:30]
How it maps to RuleOne
- The screen at /stocks/ is a first filter only. It tells you where to look, not what is inside your strike zone.
- A personal mistakes list is a good use of the /holdings/ page: when you sell or pass, write down the reason and the information you had at the time.
- Inversion sits in the Story step of the planned research agent; the agent should be built to argue against your idea, not for it.
Buffett, Munger and Graham links
- Buffett's partnership and Berkshire letters are the raw material for the mistakes list. See also Munger's inversion habit ("invert, always invert", from his Harvard talks collected in Poor Charlie's Almanack).
- Ted Williams and the strike zone: Buffett has told this story in his talks and letters, as a metaphor for patience. (I haven't confirmed the exact year.)
- Mohnish Pabrai's checklist method comes from The Checklist Manifesto (Atul Gawande), which Phil mentions.
Words to know
- Inversion: deliberately arguing the case against your own idea.
- Mistake of omission: not buying something that later does well.
- Confirmation bias: reading new information as support for what you already believe.
Try this
Open one stock page on /stocks/ you have already decided to pass on. Write two lines: what you didn't know, and what price and facts would have changed your mind. Date it. That is a mistakes-list entry in the making.
Check yourself
- Where did Phil's checklist come from?
Answer
Mostly from Buffett's described mistakes, plus Phil's own errors and ideas from Pabrai and Ackman. - Why isn't a skipped stock that later soared automatically a mistake?
Answer
If the decision was sound on the information you had, it was right at the time. Check whether the inputs have since changed. - Why is copying a guru's buy risky even when you admire them?
Answer
You don't know their true price, their margin of safety is larger than yours, and they won't tell you when they sell.
Short quotes
"You can talk yourself into thinking you know more than you know about a company real easily." (Phil, ~07:30, auto-transcribed)