Lesson Context Market Feed
SPY $746.33 +0.49%
QQQ $719.19 +0.65%
AAPL $309.61 +1.51%
MSFT $417.75 -0.32%
NVDA $217.01 -1.14%
XLK $180.80 +1.23%
Basics

The mistakes that matter most

These are not exotic edge cases. They are the recurring patterns that show up when process discipline slips.

Concepts Priority: Capital preservation Failure mode: Small errors compounding Mindset: Kill weak processes early
Key Takeaways What to take from this lesson
The dataset approved a story the market never did A decent strategy can be ruined by bad sizing
Risk Frame The page to remember
  • Do not let recent outcomes rewrite your risk standards.
  • Do not deploy anything you are not prepared to stop.
  • Do not trade a strategy you cannot explain under pressure.
Overfitting

The dataset approved a story the market never did

If the strategy needs too much parameter precision, too many filters, or too much explanation after the fact, the edge is probably not durable enough for capital.

Oversizing

A decent strategy can be ruined by bad sizing

When position size outruns evidence, ordinary drawdowns start forcing emotional decisions, and the system becomes unstable even if the signal logic stays sound.

Neglect

Unsupervised automation is still a risk choice

Not watching health, execution quality, or regime change is still an active decision. The absence of intervention can itself be the mistake.

Stubbornness

Refusing to retire weak logic compounds damage

A strategy that no longer earns desk space should be cut cleanly. Endless rescue attempts usually waste more capital and time than the original loss.