CFA Level I Exam · The Behavioral Biases of Individuals

Loss Aversion and Overconfidence Bias for CFA Level I

Updated 7 October 2026 · Fact-checked

Loss aversion is feeling losses more than equal gains, so investors hold losers and sell winners (the disposition effect). Overconfidence is unwarranted faith in your own judgment, causing excess trading and under-diversification. Loss aversion is an emotional bias, so you moderate or adapt to it. Overconfidence is a cognitive error, reduced by feedback, training and better information.

Understand Emotional Biases: Loss Aversion and Overconfidence

Behavioral biases are systematic departures from rational decision making. The CFA curriculum splits them into cognitive errors and emotional biases. Cognitive errors come from faulty reasoning or memory, so better information, feedback and training can often correct them. Emotional biases come from feelings and impulse, so they are hard to fix. You usually moderate them or adapt to them in how you build the portfolio.

Loss aversion means investors dislike losses more than they like equal-sized gains. Losing 10% hurts more than gaining 10% pleases. This comes from prospect theory. Because of it, investors often refuse to sell a losing position, hoping it will come back to the purchase price. They also sell winners too early to lock in the pleasure of a gain. This pattern is the disposition effect: selling winners too soon and holding losers too long. The result can be a portfolio of poor performers and a risk level that drifts away from the plan. Loss-averse investors may also hold too much in safe assets, which risks falling short of long-term goals.

Overconfidence is an unwarranted faith in your own reasoning, intuition and abilities. The curriculum describes two forms. Prediction overconfidence means your forecast ranges are too narrow, so you treat estimates as more precise than they are. Certainty overconfidence means you assign too high a probability to being right, so you are too sure your view will be correct. Overconfident investors tend to trade too much, which raises costs and often lowers returns. They also hold concentrated, under-diversified portfolios, underestimate risk, and may overweight familiar stocks such as their employer's shares.

In exam terms, loss aversion is an emotional bias, while overconfidence is a cognitive error. For loss aversion, the first line of defence is to moderate or adapt to it. Overconfidence can be reduced. Useful steps are training, feedback, keeping a record of forecasts against outcomes, and better information. Rules also help, such as a written investment policy and limits on diversification and trading frequency. The exam usually gives a short scenario and asks you to name the bias, its consequence, or the best way to manage it.

Key formulas to remember

Loss aversion: Pain from a loss > pleasure from an equal-sized gain; Prospect theory idea. Leads to the disposition effect: sell winners too early, hold losers too long.
Disposition effect: Sell winners early + hold losers too long; A result of loss aversion. Can create unplanned risk and poor tax outcomes.
Prediction overconfidence: Confidence ranges too narrow; Overestimating the precision of your own forecasts and knowledge.
Certainty overconfidence: Stated probability of being right > actual probability; Too much certainty that your view is correct.
Consequences of overconfidence: Excess trading + under-diversification + underestimated risk; Excess trading raises costs and typically lowers net returns.
Treatment of emotional biases (such as loss aversion): Moderate or adapt, not correct; Emotional biases are harder to fix than cognitive errors. Adapt the plan to the bias where needed.
Treatment of overconfidence (a cognitive error): Reduce with feedback + training + better information, supported by rules and diversification; Cognitive errors can generally be corrected. Forecast records, a written policy and diversification rules also help.

How to solve Emotional Biases: Loss Aversion and Overconfidence questions

Use this method for any scenario question on loss aversion or overconfidence.

1Read the investor's behaviour, not the label. Note what they did: held, sold, traded, or concentrated.
2If they sell gains early and hold losses, or avoid realizing a loss, think loss aversion and the disposition effect.
3If they trade often, trust narrow forecasts, hold few stocks or are very sure of their view, think overconfidence.
4For overconfidence, decide the type: narrow ranges means prediction; too sure of being right means certainty.
5Identify the harm asked about: costs, poor diversification, risk drift, or missed goals.
6Remember loss aversion is an emotional bias, so it is moderated or adapted to. Overconfidence is a cognitive error, so feedback, training, forecast records and better information can reduce it, with rules and diversification helping too.
7Eliminate the option that names a different bias, or that says information alone will fix loss aversion.
8Check that your final choice matches the exact wording of the question: bias, consequence or remedy.

Quickest way: Behaviour-to-bias shortcut

When to use it: Use when you have about 90 seconds and the stem describes an investor's actions.

Holds a loser or sells a winner early: loss aversion.
Trades heavily, concentrated holdings, narrow forecast ranges or strong certainty: overconfidence.
Question asks for the remedy: pick the option on discipline, diversification, an IPS, feedback, or tracking forecast accuracy.
Drop any option claiming loss aversion is simply fixed by more data. For overconfidence, feedback and information are valid parts of the remedy.
If two options remain, choose the one that matches the exact harm in the stem.

Common mistakes in Emotional Biases: Loss Aversion and Overconfidence

Treating the disposition effect as a separate bias unrelated to loss aversion.
The two terms appear close together and look like different ideas.
Fix: Remember the disposition effect is the trading result of loss aversion: winners sold early, losers held.
Saying loss aversion means investors avoid all risk.
The name suggests general risk avoidance.
Fix: It is about the asymmetry between losses and gains. It can lead to holding losers, which leaves the portfolio with a risk level that may not match the plan.
Mixing up prediction and certainty overconfidence.
Both involve too much faith in your own view.
Fix: Prediction concerns the width of estimate ranges. Certainty concerns the probability you give to being right.
Claiming overconfident investors hold diversified portfolios because they trade a lot.
Heavy trading is mistaken for broad holdings.
Fix: Overconfident investors typically hold concentrated, under-diversified portfolios while trading excessively.
Choosing 'provide more information' to fix loss aversion.
Information works well for cognitive errors, so it feels like a general cure.
Fix: Loss aversion is an emotional bias. Choose moderation or adaptation: rules, an IPS, diversification and discipline.
Classing overconfidence as an emotional bias that cannot be corrected.
Overconfidence feels like a personality trait, so it seems fixed.
Fix: It is a cognitive error. Training, feedback, forecast records and better information can reduce it, and rules and diversification help too.
Thinking overconfident investors earn higher returns because they act more.
Activity feels like skill.
Fix: Excess trading adds costs and generally reduces returns. Name this effect when asked.

Worked examples

Example 1

An investor bought two shares at the same time. Share X has risen 30% and Share Y has fallen 25%. She sells X to bank the profit and keeps Y, saying she will sell once it recovers to her purchase price. Which bias best explains her behaviour? A) Overconfidence B) Loss aversion C) Status quo bias

Show the solution

Note the actions: she sold a winner and kept a loser until it returns to cost.
This is the disposition effect, selling winners early and holding losers.
The disposition effect comes from loss aversion: she avoids realizing the pain of a loss.
Option A does not describe the refusal to realize losses. Option C is a preference to leave holdings unchanged, but she did act by selling Share X, so it does not explain her pattern.

Answer: B) Loss aversion

Example 2

A fund manager trades his personal account daily, holds only three technology stocks, and says there is a 95% probability that each pick will beat the market. He does not give forecast ranges. His past picks have beaten the market only about half the time. Which is the most appropriate description and remedy? A) Loss aversion; hold losers longer B) Certainty overconfidence; use feedback from a forecast record and a diversification rule C) Prediction overconfidence; trade more often to test his views

Show the solution

Heavy trading and a concentrated three-stock portfolio point to overconfidence.
He states a 95% probability of being right, but his record is about 50%. His stated probability of being right exceeds his actual hit rate, and the stem says nothing about the width of forecast ranges. That is certainty overconfidence.
Overconfidence is a cognitive error, so it can be reduced. Feedback from tracking forecasts against outcomes shows him his real hit rate. Training and better information help, and a diversification rule and a written policy limit the damage.
Option A names the wrong bias, and holding losers longer is not a remedy. Option C names the wrong type, because the problem is too high a probability of being right rather than narrow ranges. Trading more often would add costs and worsen the overconfidence.

Answer: B) Certainty overconfidence; use feedback from a forecast record and a diversification rule

Exam tips

Scenario stems rarely name the bias. Match the behaviour to the bias before reading the options.
Know both forms of overconfidence and the one-line difference: narrow ranges versus too-high probability of being right.
Loss aversion is an emotional bias: moderate or adapt. Overconfidence is a cognitive error: feedback, training and better information can reduce it, and rules and diversification help.
With three options and no penalty for wrong answers, eliminate the bias that does not fit the behaviour, then guess between the rest if needed.
Link each bias to its portfolio effect: loss aversion to disposition effect and risk drift, overconfidence to excess trading and under-diversification.

Practice questions from The Behavioral Biases of Individuals

Emotional Biases: Loss Aversion and Overconfidence in other exams

The same ground in other exams, if you are preparing for more than one or want another angle on it.

NISM CertificationsEmotional Biases

Emotional Biases: Loss Aversion and Overconfidence: frequently asked questions

What is the disposition effect and how does it relate to loss aversion?

The disposition effect is the tendency to sell winning investments too early and hold losing ones too long. It is the trading result of loss aversion, because realizing a loss feels more painful than the pleasure of an equal gain.

How does loss aversion affect portfolio decisions?

It can lead investors to hold losers in hope of breaking even and to sell winners prematurely. This can leave a portfolio of weak performers and a risk level that no longer matches the plan. It may also push investors toward overly safe assets that make long-term goals harder to reach.

What is the difference between prediction and certainty overconfidence?

Prediction overconfidence is setting forecast ranges that are too narrow, so you overstate how precise your estimates are. Certainty overconfidence is assigning too high a probability to being right. Read the stem for ranges versus confidence in being correct.

How is overconfidence managed?

The curriculum treats overconfidence as a cognitive error, so it can be reduced. Training, feedback, a record of forecasts versus results, and better information all help. A written investment policy and diversification and trading rules add further protection.