What is Anchoring Bias?
Anchoring is leaning too heavily on the first number you saw when judging a value, then adjusting too little away from it. Investors often anchor on the price they paid or on a past high, as if the market knows or cares what those numbers were.
Why Anchoring Bias matters
A purchase price is a fact about you, not about the investment, so decisions anchored to it can ignore what has changed.