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.

To avoid confirmation bias and emotional decision-making, investors should pre-define objective 'kill criteria' for each investment. These criteria should specify a future state (e.g., poor capital allocation) and a date, providing a clear signal to exit a position when the thesis is broken.

A common mistake is altering an investment thesis to justify holding a losing stock, known as "thesis creep." A better approach is to sell immediately when the original thesis is proven wrong, rather than creating a new narrative to accommodate a falling price and avoid admitting a mistake.

Effective decision-making is not about being right all the time; it's about speed and discipline. Top traders are correct only about 55% of the time. Their real skill lies in quickly recognizing the 45% of wrong decisions and cutting their losses without ego. This principle applies to all leadership.

Post-mortems of bad investments reveal the cause is never a calculation error but always a psychological bias or emotional trap. Sequoia catalogs ~40 of these, including failing to separate the emotional 'thrill of the chase' from the clinical, objective assessment required for sound decision-making.

The best macro traders (Jones, Druckenmiller, Soros) are defined by their ability to discard a viewpoint the moment facts change, rather than defending it out of ego. This intellectual flexibility is crucial for survival and success, as clinging to a wrong idea is a far greater error than admitting a mistake.

Investors spend hours on due diligence before buying but rarely pre-define their selling criteria. This leads to emotional decisions, typically selling after a period of underperformance, which undermines the initial long-term thesis. A pre-defined sell plan is crucial for success.

A robust investment strategy relies on a long-term, directional thesis about the world. Don't react to market volatility; only adjust your portfolio when your fundamental, long-term beliefs about the market have changed.

True investment maturity isn't about holding through drawdowns. It's about recognizing when new information invalidates your thesis and selling immediately. The common instinct to defend a position by buying more is a costly mistake that turns event-driven plays into distressed holdings.