Recognize the mistake before it becomes expensive.

A compelling theme is treated as proof that one company, fund or price must succeed.

Separate the industry story from the security’s financials, structure, valuation and risks.

A $20 stock is assumed to be cheaper than a $200 stock.

Compare market capitalization, enterprise value and per-share fundamentals—not the number printed beside the ticker.

A market order is submitted in a thin or fast market without considering the spread.

Choose execution certainty or price control deliberately and review the live quote and liquidity.

Conviction determines position size while the dollar consequence of being wrong remains unknown.

Model the adverse scenario first, then size exposure at the portfolio level.

A falling price is automatically labeled a bargain—or a rising price proof of quality.

Revisit the evidence, expectations and risk; price direction alone does not establish value.

A 30% loss is treated as if a 30% gain will restore the starting value.

Calculate from the new, smaller base and let drawdown tolerance influence sizing before the trade.

A fund or stock is selected mainly because its latest return looks exceptional.

Ask what drove the result, whether exposure changed and what expectations are now embedded in the price.

Owning many tickers is assumed to remove concentration.

Look through holdings to sectors, factors, regions and common economic drivers.

The plan models the quoted price but ignores spreads, fees, financing and taxes.

Estimate the full round-trip economics and test whether the expected edge survives realistic costs.

One P/E or yield number is used to label an investment good or bad.

Compare accounting quality, growth, capital structure, cyclicality and the metric’s calculation method.

A dividend reinvestment or recurring purchase replaces shares after a loss without being noticed.

Map the full 61-day window across relevant accounts and check scheduled acquisitions.

The original plan changes only because realizing the mistake feels uncomfortable.

Record the thesis, downside and invalidation evidence before entry; review process separately from outcome.