To avoid emotional, performance-chasing mistakes, write down your selling criteria in advance and intentionally exclude recent performance from the list. This forces a focus on more rational reasons, such as a broken investment thesis, manager changes, excessive fees, or shifting personal goals, thereby preventing reactionary decisions based on market noise.

To combat the emotional burden of binary sell-or-hold decisions, use the "Go Havsies" method. Instead of selling a full position, sell half. This simple algorithm diversifies potential outcomes—you benefit if it rises and are protected if it falls—which significantly reduces the psychological pain of regret from making the "wrong" choice.

The goal of diversification is to hold assets that behave differently. By design, some part of your portfolio will likely be underperforming at all times. Accepting this discomfort is a key feature of a well-constructed portfolio, not a bug to be fixed.

The sign of a working diversification strategy is having something in your portfolio that you're unhappy with. Chasing winners by selling the laggard is a common mistake that leads to buying high and selling low. The discomfort of holding an underperformer is proof the strategy is functioning as intended, not that it's failing.

Gardner notes that whenever he has broken his own rule and invested an "exciting amount" into a new idea, it has generally failed. This emotional excitement leads to poor decision-making and oversized bets on unproven theses. Strict discipline on initial position sizing is a crucial defense against one's own biases.

To combat endowment effect and status quo bias, legendary trader Paul Tudor Jones advises viewing every position as if you were deciding to put it on today. This creates a zero-based mindset, forcing you to justify each holding's continued place in your portfolio.

Rather than passively holding a stock, the "buy and optimize" strategy involves actively managing its weighting in a portfolio. As a stock becomes more expensive relative to its intrinsic value, the position is trimmed, and when it gets cheaper, it is increased, creating an additional layer of return.

To combat emotional decision-making, Eddie Elfenbein’s strategy mandates replacing exactly five of 25 stocks each year. This rigid structure forces patience and prevents impulsive trades, even when he feels tempted to sell a poorly performing stock. This system prioritizes long-term strategy over short-term reactions.

Suboptimal selling is often driven by fear: a position gets "too big" or you want to lock in gains. A better approach is to only sell when you find a new investment you "love" more. This forces a positive, opportunity-cost framework rather than a negative, fear-based one, letting winners run.