Portfolio Construction & Management: Allocation, Sizing, and Diversification

Portfolio Construction Fundamentals

• 🎯 Portfolio construction and management involves determining the size of each stock and the total number of stocks in a portfolio.
• 💡 The spectrum of portfolio structuring ranges from highly concentrated approaches, like Charlie Munger's with few positions, to broadly diversified ones, such as Tom Gayner's with many companies.
• 📊 For allocation, a structured approach can involve defining full position size, starter position size, and prospect/feeler positions, with examples like 6.25% for a full position and 1.5% for a starter.

Number of Companies and Diversification

• 🧩 Determining the number of companies depends on allocation strategy; for instance, 5% positions imply 20 companies for a fully allocated portfolio.
• ⚠️ Owning too many companies, like 250+, can make tracking difficult for individual investors, questioning the benefit for average investors.
• 🧠 The decision on how many companies to own is influenced by individual comfort levels, mindset, and the investor's approach to managing emotional biases.
• 🔍 Diversification is more critical early in portfolio building to spread bets, becoming a lesser concern as the portfolio matures, though avoiding over-concentration in one sector is still important.

Portfolio Management Strategies

• 🚀 The concept of "letting profits run" is contrasted with trimming positions, emphasizing that selling should ideally be based on changes in business fundamentals rather than stock price appreciation.
• 💡 A key principle is to focus on the business itself rather than stock price volatility to make sound decisions, potentially by obscuring the price during analysis.
• ✍️ Establishing an investment thesis in writing is crucial for remembering the rationale behind buying or holding a company, aiding in future analysis and decision-making.
• 🚫 Rebalancing, common in index funds, involves selling appreciated assets to buy underperforming ones. This is generally not recommended for individual stocks as it can counteract the strategy of letting profits run and potentially cut off successful investments.

Behavioral Biases in Investing

• 🎭 Investors can develop attachment biases to their holdings, similar to familiarity with a local sports team, which might lead to overestimating a company's prospects or delaying necessary sell decisions.
• 🧠 The "Peter Lynch idea" of sometimes the best investment is one you already own can be a persistent bias, but it's important to remember Lynch's own investing style involved shorter holding periods and a large number of stocks.
• ⚠️ Distinguishing between investing and speculating/gambling is vital, as highly concentrated, volatile bets or significant allocations to assets like Bitcoin are not considered investing by some definitions.
• ✅ Writing down the initial investment thesis and referring back to it helps in evaluating whether the original reasons for investing are still valid, aiding in management decisions.