Personal Investment Philosophy & Process

The Foundation: Circle of Competence

What Is Circle of Competence?

Warren Buffett and Charlie Munger have repeatedly emphasized that the most important rule of investing is to stay within your circle of competence. This is not false modesty-it is brutal honesty about what you truly understand deeply enough to make a bet on.

Your circle of competence is the set of industries, business models, competitive dynamics, and market structures that you understand well enough to identify when something is mispriced. It is NOT the set of stocks you can name. It is the set of business fundamentals you can analyze accurately and the competitive moats you can evaluate credibly.

Most investors dramatically overestimate their circle of competence. They see a company they use and assume they understand it. They read one article about an industry and think they grasp its dynamics. Buffett's circle was narrow-textiles, insurance, utilities, newspapers, soft drinks. He stayed there. Over decades, he expanded it carefully, but always with humility about the boundaries.

Your circle has three dimensions: breadth (how many industries you understand), depth (how deeply you understand each), and edges (where the boundaries are). A narrow but deep circle beats a broad but shallow one.

Assessing Your Circle Honestly

To assess your circle, answer these questions ruthlessly:

Industry knowledge: What industries do you work in, study professionally, or understand from family/peer experience? Not what you read about-what you actually understand operationally. If you've managed supply chains, you understand manufacturing complexity. If you've worked in tech, you understand software scalability and network effects. If you've been in healthcare, you understand regulatory dynamics and reimbursement pressures.

Competitive moat analysis: Which specific competitive advantages can you evaluate? Can you judge whether a software company's moat is real network effects or just switching costs? Can you assess whether a brand's pricing power is durable or fading? Can you differentiate between true operational excellence and temporary cost advantages?

Macro and market structure: Do you understand the macro cycles affecting your industries? Can you predict where interest rates will go meaningfully better than the market? Or is that outside your circle? Do you understand how consolidation dynamics work in specific sectors?

Financial statement literacy: Can you read financial statements not just mechanically (current ratio, debt/equity) but interpret them to understand what management is actually doing operationally? Can you spot when accounting choices are masking business reality?

Write down your honest circle. Include: (1) Industries where you have deep operational knowledge. (2) Competitive advantages you can evaluate. (3) Financial and macro dynamics you understand. (4) Explicit boundaries-industries you avoid because you don't understand them.

Circle of Competence Reality Check Your circle is smaller than you think. If you can't explain why a business will maintain its competitive advantage for 10 years, it's outside your circle. If you need to guess about macro or market structure, it's outside your circle.

Expanding Your Circle Carefully

You cannot expand your circle by reading. You expand it through deep study combined with pattern recognition over time. When Buffett entered insurance, he spent years studying the economics, reading annual reports, and understanding the underwriting cycle before making large bets. When he moved into utilities, he did similar work.

To expand your circle, pick ONE adjacent industry or business model. Commit to 6–12 months of deep study: read 20+ years of annual reports from competitors, understand the regulatory environment, talk to practitioners if possible, track the industry for quarters to see how management decisions actually play out operationally. Only then can you expand your circle with real confidence.

Most investors never expand their circles meaningfully. They stay narrow their whole careers. This is fine. Buffett's 50-year track record was built on a relatively narrow circle that he understood exceptionally deeply. Depth beats breadth.

The 5-Stage Research Workflow

Stage 1: Sourcing - Finding Ideas Worth Researching

Great investment ideas don't come randomly. They come from structured sourcing channels that naturally produce candidates in your circle of competence. Build 3–5 sourcing channels and visit them regularly.

Screener-based sourcing: Use ValueMarkers screener with your preferred guru strategy (Graham Defensive, Deep Value, Magic Formula, ROIC Champions, Buffett Quality). Run the screener monthly. This naturally surfaces stocks that meet multiple fundamental criteria. The discipline: only source from your circle. If all results are tech companies and you don't understand software economics, adjust the screener or skip the results.

13F filings and value investor disclosure: Track what Berkshire, Baupost, Pershing Square, and other high-conviction investors are buying and selling. This is not about copying them-it's about finding stocks interesting enough to merit deep research from people whose criteria you respect. When Buffett buys a stock, it passes his triage filters. When Marks's Oaktree adds to a position, it's worth investigating why.

Investor letters: Read Berkshire shareholder letters, Oaktree memos, Baupost letters, Pershing Square presentations. These discuss not just specific holdings but investment thesis categories. Buffett's letters often highlight which industries he finds attractive or unattractive. This shapes where you source.

Special situations: Spin-offs, bankruptcy reorganizations, secondaries, private company IPOs, merger arbitrage. These create inefficiency. CMBG3 (Special Situations focused funds) and SEC filings alert you to events. The discipline: only pursue special situations you understand. Do not source merger arbitrage if you don't understand deal risk pricing.

Financial statements and earnings calls: For companies already in your circle, read earnings releases as they come out. Listen to calls. When management discusses headwinds or opportunities, make note. Often the sourcing moment is not "I found a cheap stock" but "This company is investing heavily in X, which suggests management confidence, and the market hasn't priced it in yet."

Sourcing Discipline Do not source randomly from investment blogs, Reddit, or TV tips. Do not source from the news when something drops 50%. Source systematically from channels that align with your circle. Quality of ideas is everything.

Stage 2: Triage - Screening 30 Ideas to 5 Deep-Dives

You cannot deep-dive every idea. You need a triage filter that eliminates 80–90% of candidates in 30 seconds per stock. This is where ValueMarkers VM Score, Quality Triple Check, and quick valuation filters help.

Triage filter 1: ValueMarkers VM Score and tier-appropriate indicators. If you're an Analyst tier subscriber, you have access to all 120 indicators. For triage, use a small subset: (1) VM Score above your threshold (e.g., 55+). (2) Quality pillar above your threshold (e.g., 50+). (3) Integrity pillar above your threshold (e.g., 60+, to avoid Beneish red flags). (4) Debt/Equity below 1.5 (to avoid overleveraged situations). Stocks that fail these filters are out. This cuts your list by 60%.

Triage filter 2: Quality Triple Check-Piotroski F-Score, Altman Z-Score, Beneish M-Score. Piotroski above 5 means improving operational fundamentals. Altman Z above 2.9 means low bankruptcy risk. Beneish M above -1.78 is a red flag for accounting manipulation. If a stock fails 2 of 3, it's out. This cuts another 20%.

Triage filter 3: Valuation sanity check. What's the stock trading at on earnings, sales, cash flow, book value? Is it in the bottom 20% of the market on these metrics (indicating cheapness)? Or is it expensive? If cheap on none of these metrics, and you don't have a specific thesis about why it's mispriced, it's out. This cuts another 10%.

Triage filter 4: Moat intuition check. Reading the business description and recent news, do you sense any competitive advantage? If you read "commodity business with 3% margins, lots of competition" and nothing else, it's probably out unless you have a specific turn thesis.

After triage, you have 5–10 candidates per month. These move to deep dive.

Triage Discipline Triage is not research. It is filtering. It should take 30 seconds per stock. If you're spending 5 minutes on triage, you're doing research. Use ValueMarkers indicators to automate triage.

Stage 3: Deep Dive - The 40-Hour Research Project

When you deep-dive a stock, you are trying to answer one question: Is this business worth more than the market is paying? To answer it, you need to understand three things: (1) What is the sustainable competitive advantage? (2) What is the normalized earnings power? (3) What should I pay for that?

Part 1: Financial analysis (10 hours). Read 5–10 years of annual reports and earnings calls. Specifically:

• Revenue trends: growing, stable, or declining? Why?

• Gross margin trends: improving, stable, or declining? This reveals pricing power and operating leverage.

• Operating margin: Can management control costs? Are there operating leverage opportunities?

• Return on equity and ROIC: Is capital deployed efficiently? Is ROIC > cost of capital?

• Cash flow: Is earnings quality high (cash flow tracking earnings) or low (accounting earnings inflated)?

• Capital allocation: Is management buying back stock (often a sign of undervaluation or misallocation)? Increasing debt? Investing in new business lines?

Document findings in a spreadsheet: 10-year revenue, margins, earnings, cash flow, FCF, ROIC, debt/equity, dividend. Plot trends. You should be able to see whether fundamentals are improving, deteriorating, or cycling.

Part 2: Competitive advantage analysis (15 hours). Now you're investigating moat durability. For each industry, the competitive advantages come from different sources:

• Brand and pricing power: Can this company raise prices without losing customers? Does the brand justify premium pricing? Test this against peers. Does Coca-Cola charge more than store brand cola? Yes. Does Facebook have pricing power on ad rates? Yes. Does a regional bank? No.

• Cost leadership: Is the company a low-cost producer? Is this durable? Southwest Airlines has lower costs than legacy carriers. But is this sustainable with unionization pressures and fuel costs?

• Network effects: Does the value increase with more users? Facebook, credit card networks, stock exchanges. Durability depends on switching costs and network lock-in.

• Switching costs: How hard is it for customers to switch? Enterprise software has high switching costs. Commodity chemicals have low switching costs.

• Regulatory moat: Does regulation protect this business? Utilities have regulatory moats. Telecom companies do. Brokers don't anymore.

• Intangible assets: Patents, licenses, relationships, data. How durable? When do patents expire?

For each moat, ask: How will this advantage erode over 10 years? What's the threat? When might it disappear? If you can't articulate a durability thesis, the moat may not be real.

Part 3: Valuation analysis (15 hours). Now you value the business under different scenarios:

• Historic multiples: What has this stock traded at on P/E, P/B, EV/EBITDA historically? Is current valuation in the bottom 25%? (indicating cheapness relative to history)

• Peer comparison: What do competitors trade at on the same multiples? Is this stock cheaper? If it's cheaper, why? (higher risk, lower quality, temporary headwinds, or genuine mispricing?)

• DCF** valuation**: Project 5–10 years of free cash flow under a base case, conservative case, and upside case. Use a WACC of 8–10% depending on risk. Calculate terminal value. DCF is not precision-it's a range. If your fair value range is $50–70 and it's trading at $40, it's potentially attractive.

• Margin of safety: What discount to your fair value range provides enough margin for error? Graham suggested 33%. Munger suggested 10–15% depending on risk. If you value something at $50–70 and it's trading at $35, you have a 40% margin. If it's trading at $48, you have a 5% margin. Does that margin justify the risk?

Deep Dive Investment Thesis Write your thesis in one page: (1) What is the business? (2) What is the competitive advantage? (3) Why is it mispriced? (4) What's the bear case? (5) What's your fair value estimate? (6) What could go wrong?

Stage 4: Decision - Conviction Scoring and Position Sizing

You now have deep research on a stock. You've identified a mispricing. But do you act? And if so, how much do you bet?

Conviction scoring: Rate your conviction on three dimensions:

• Thesis confidence (1–10): How certain are you about the competitive advantage? How certain about normalized earnings power? If you're 9/10 confident (e.g., Berkshire buying Berkshire), you can bet big. If you're 6/10 confident (you think the moat is real but there's execution risk), you bet smaller.

• Valuation confidence (1–10): How certain are you about fair value? If you've done 40 hours of modeling and narrowed to $50–60, and it's trading at $40, you're 8/10 confident. If you're uncertain about growth rates and your range is $30–100, you're 3/10 confident.

• Timing confidence (1–10): How certain are you that mispricing will correct in your timeframe? This is the hardest. Buffett bought some stocks and waited 10 years. Others he waited 2 years. If you're 6/10 confident (you think it will correct within 3 years but unsure), you need a larger margin of safety.

Overall conviction score: Weight these. A stock with 8/10 thesis, 7/10 valuation, and 5/10 timing confidence is a 7/10 conviction. A 9/10 on all three is a slam dunk. A 5/10 on thesis is a pass.

Position sizing using Kelly Criterion logic: The Kelly Criterion formula is: f* = (bp - q) / b, where b is odds payoff, p is win probability, q is loss probability. Simplified: if you're 65% confident a stock will outperform, with 2x upside and 50% downside, Kelly suggests 10–15% of your portfolio. But use "half-Kelly" (6–8%) for safety.

In practice:

• Conviction 8+/10: 8–12% position size (your largest bets)

• Conviction 6–7/10: 3–6% position size

• Conviction 4–5/10: 1–2% position size

• Conviction <4/10: Don't invest

This creates a portfolio where your highest-conviction ideas are meaningfully larger than your lower-conviction ones, but you're never betting too much on any single stock.

Stage 5: Monitoring - Quarterly Review and Thesis Kill Triggers

After you buy, your job is NOT to watch the stock price. It is to monitor whether your thesis is still intact. This requires discipline: quarterly review of fundamentals, not daily watching of price.

Quarterly review checklist:

• Did the company release earnings? What changed in revenue, margins, capital allocation, competitive positioning?

• Did the competitive advantage strengthen or weaken? Any new competitors? Lost customers? Pricing pressure?

• Did the valuation change? Is your fair value estimate still $50–70? If it's now trading at $85, time to reconsider.

• Any changes in macro environment that affect this business? (interest rates, regulation, customer spending, supply chain)

• Is there any change in management or strategy that signals capital allocation decisions?

Thesis kill triggers: These are pre-specified conditions that would cause you to sell, regardless of stock price:

• Competitive advantage deteriorates: A key customer leaves. A competitor introduces a superior product. Market share drops 20%. Margins compress permanently.

• Financial deterioration: Operating cash flow turns negative. Debt/Equity exceeds your comfort threshold. Return on incremental capital drops below cost of capital.

• Management red flags: Aggressive accounting. Change in incentive structure. Key executive departure without adequate succession plan.

• Valuation: Stock rises to 2x your fair value estimate. You no longer have margin of safety. Even if thesis is intact, better opportunities exist elsewhere.

• Opportunity cost: You find a stock you're more confident in. Your capital is finite. Redeploy to higher-conviction ideas.

By pre-specifying triggers, you remove emotion from the exit decision.

The Investment Policy Statement (IPS)

An Investment Policy Statement is a written document that codifies your investment approach. It is the single most important document you'll create. It is not meant to be changed frequently-it is meant to be your anchor when fear and greed push you to break your discipline.

A world-class IPS includes:

1. Investment objective: What are you investing for? Retirement? Kids' education? Long-term wealth? What return do you need to achieve your goal?

2. Risk tolerance: How much can your portfolio decline before you panic sell? If your portfolio falls 30%, can you sleep? Or do you need to limit downside to 15%? This is honest question, not theoretical.

3. Time horizon: When do you need this money? If you need it in 5 years, you take different risk than 20 years.

4. Asset allocation: What % in stocks vs bonds vs cash? What % in your circle of competence sectors vs diversified? A concentrated value investor might be 90% stocks / 10% bonds. A conservative investor might be 60% stocks / 40% bonds.

5. Circle of competence: Explicit list of industries you focus on and avoid.

6. Valuation framework: What P/E, P/B, EV/EBITDA ranges do you target? What margin of safety do you require?

7. Position sizing: How large is your largest position? What's your target for average position size?

8. Rebalancing rules: When do you rebalance? Annually? Quarterly? When allocations drift by 5%?

9. Dividend and cash management: Do you reinvest dividends? How much cash do you hold?

10. Exit discipline: What makes you sell? (thesis broken, full valuation, opportunity cost, position sizing)

11. Review frequency: When do you review and update your IPS? Annually? Every 3 years? (Don't change it constantly.)

Buffett has an informal IPS. Munger has an informal one. Write yours down.

Building Your Decision Journal

A decision journal is your single most powerful debiasing tool. Every time you invest (or actively decide not to invest), document:

1. What was your thesis? (1-paragraph summary)

2. What was the investment or non-investment price?

3. What was your conviction score? (1-10)

4. What was your margin of safety?

5. What was your timeframe for the thesis to play out?

6. What could prove you wrong?

Every quarter or annually, pull up your old entries. Update them with what actually happened:

1. Did your thesis play out as expected?

2. What was the stock's actual return?

3. Did you correctly assess the competitive advantage?

4. Did you correctly value the business?

5. What did you learn?

Over 5 years, you'll accumulate 50–100 entries. You'll start to see patterns: Do you overestimate moat durability? Do you tend to be too bearish on macro? Do you underestimate turnaround timelines? This feedback loop is how you improve.

Your Personal Investment Checklist

Munger often says, "I've got a philosophy that's very simple: if I'm 90-some percent sure, I will do it." But how do you get to 90% sure? Use a checklist.

Before you invest, walk through:

1. Competitive advantage: Does this business have sustainable competitive advantage? (Yes/No/Maybe-if Maybe, it's a no.)

2. Financials healthy: Is ROE > 12%? Is debt reasonable? Is cash flow positive and growing? (Yes/No)

3. Management aligned: Does management own stock? Are capital allocation decisions wise? (Yes/No)

4. Valuation reasonable: Is it trading below my fair value estimate with margin of safety? (Yes/No)

5. In my circle: Do I understand this business and industry well enough to make a bet? (Yes/No/Maybe-if Maybe, it's a no.)

6. Business model durable: Will this business look the same in 10 years, or is there disruption risk? (Yes/No)

If you answer "No" or "Maybe" to more than 1 question, don't invest. This checklist prevents 80% of bad investments.

Self-Practice Prompts

1. Define Your Circle: Write down your legitimate circle of competence in 3–4 industries. For each, explain specifically what gives you edge. Be honest about boundaries.

2. Screener Deep Dive: Run ValueMarkers screener for Magic Formula (or your preferred strategy). Pick one result that passes your triage filters. Do a 5-hour research project (not 40 hours) and write a 1-page thesis.

3. Reverse Engineer a Great Investment: Pick one Berkshire holding (e.g., Apple, Moody's, American Express). Find the price Buffett bought at, and his estimated cost basis. Calculate his return. Then work backwards: what would his valuation thesis have been at purchase price? What was he seeing that the market wasn't?

4. Decision Journal Entry: For a stock you own or are considering, write a decision journal entry. Document your thesis, conviction, valuation, and what could prove you wrong.

5. Investment Policy Statement Draft: Write a 1-page draft IPS covering objectives, risk tolerance, circle of competence, position sizing, and rebalancing rules. Share with a trusted peer for feedback.

6. Build Your Triage Filter: Specify your exact triage criteria using ValueMarkers indicators. What VM Score threshold? What Quality pillar threshold? What debt/equity ceiling? What Piotroski minimum? Write it down.