The Evidence

The research behind investing on rules, not reflexes.

Decades of behavioral-finance research on how investors actually behave, and what it means for building, reviewing, and sticking to a plan.

Behavioral finance6 min readJul 4, 2026

Rules beat willpower: the case for a commitment device

The investors who stick to a plan aren't stronger in the heat of the moment. They set things up so the heat of the moment never gets a vote.

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Rule design7 min readJul 4, 2026

Why backtests lie, and how to read one honestly

A backtest is a hypothesis, not a promise. The same math that makes a strategy look brilliant is exactly what breaks it live.

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Behavioral finance5 min readJul 4, 2026

The calm plan and the scared trade

You can't imagine how you'll feel in a crash while the market is calm, and you can't think clearly once it isn't. That gap is where plans go to die.

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Behavioral finance6 min readJul 4, 2026

The illusion of knowledge: why more research can make you worse

Given more data, expert gamblers didn't get more accurate, only more confident. Investors have the same problem, with more screens.

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AI & investing6 min readJul 4, 2026

Why you shouldn't let an AI agent run your portfolio

The most rigorous test yet ran AI trading agents over 20 years and 100+ stocks. They lost to buy-and-hold, by making the same mistakes emotional humans make.

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Behavioral finance7 min readJul 3, 2026

Why checking your portfolio hurts your returns

Four decades of research on real brokerage accounts on what frequent watching does to your decisions, and the case for a calmer review cadence.

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