Privat Capital holds a concentrated portfolio of 16-17 stocks. This strategy forces deep conviction in each position and ensures that winners have a meaningful impact on fund performance. Over-diversification can dilute both research focus and the potential returns from a fund's best ideas.

Regularly re-evaluate your investment theses. Stubbornly holding onto an initial belief despite new, contradictory information can lead to significant losses. This framework encourages adaptation by forcing you to re-earn your conviction at regular intervals, preventing belief calcification.

Effective long-term investing isn't about predicting the future but acknowledging you can't. This mindset forces broad diversification across different economic forces (not just asset classes), a long time horizon, and sufficient liquidity to avoid becoming a forced seller during downturns.

Tim Guinness's firm uses 30 equal-weighted stocks to diversify risk. This forces a "one-in, one-out" policy, compelling the team to sell their least-favored holding to add a new one, thus overcoming the common investor weakness of being poor at selling.

Analysis of Keynes's portfolio reveals a subtle skill: his true value-add came from ensuring his lowest-conviction ideas received minimal capital. Over his career, his bottom five positions shrank from 11.7% to just 6% of his portfolio, demonstrating a disciplined approach to managing risk on less-certain bets.

Many investors wrongly equate high conviction with making a large initial investment. A more evolved approach is to start with smaller at-cost positions, allowing a company's performance to earn its eventual large weighting in the portfolio. This mitigates risk and improves decision-making.

Allocate more capital to businesses with a highly predictable future (a narrow "cone of uncertainty"), like Costco. Less predictable, high-upside bets should be smaller positions, as their future has a wider range of possible outcomes. Conviction and certainty should drive allocation size.

By seeding new positions at ~0.5% and rarely exceeding 1% at cost, the fund mitigates the behavioral risk of averaging down too aggressively into a failing investment. This disciplined approach prevents a small mistake from becoming a large portfolio loss.

In 2008, Howard Marks invested billions with conviction while markets crashed, yet he wasn't certain of the outcome. He held the paradox of needing to act decisively against the crowd while simultaneously accepting the real possibility of being wrong. This mental balance is crucial for high-stakes decisions.