Notes

Valuation, market data, and what breaks when you build this stuff yourself.

• Why Buffett’s first rule is “never lose money”

  Lose 50% and you need 100% to get back to even. The asymmetry is the whole rule — and the reason refusing to take a small loss is how you end up with a big one.

  12 September 2026

• Time in the market vs timing the market

  Over one day the S&P 500 is close to a coin flip. Over twenty years it has never lost. Only the waiting changed.

  2 September 2026

• Why I built a stock simulator with a real research stack

  Every broker gives paper trading away. The tools are the part that took two years.

  27 August 2026