Nasdaq will soon let you trade 23 hours a day. Buffett's advice was to barely trade at all.

🕐 The always-on market: Nasdaq's 23-hour trading day, targeted for 6 December.
🏛 The punch card in practice: Berkshire's portfolio, built to be held.
🔁 Buying back below value: Companies repurchasing shares while trading under fair value.

Buffett stepped down as Berkshire's chairman on Friday. And yet one of his ideas is more relevant than ever.

Imagine a card with 20 punches for your whole investing life. Every purchase uses one. You'd think far harder about each decision, and probably end up far better off.

From December, Nasdaq plans to trade 23 hours a day. More hours means more prices to react to, but that shouldn’t be interpreted as more reasons to act.

Which company would you happily spend one of your 20 punches on, and why?