Risk Aversion vs Loss Aversion Explained

Definition:

• Risk aversion = preferring certain outcomes over uncertain outcomes with the same expected value.
• The classic example: would you take a guaranteed GBP 50 or a 50/50 chance of GBP 0 or GBP 100? Both have expected value of GBP 50. A risk-averse person prefers the certain GBP 50.

It's rational:

• The decreasing marginal utility of wealth justifies risk aversion economically.
• Most people would feel a much bigger benefit from gaining GBP 1,000 if they had GBP 5,000 than if they had GBP 1,000,000.
• This concave utility function automatically produces risk aversion.

It's symmetric:

• Risk-averse person prefers certain GBP 50 over 50/50 of GBP 0/GBP 100 (gains).
• Same person prefers certain GBP -50 over 50/50 of GBP 0/GBP -100 (losses).
• The preference for certainty applies equally on both sides.

Measuring risk aversion:

• Investment surveys often ask: 'How much certainty equivalent would you accept for a 50/50 chance of GBP 100 or GBP 0?'
• Answer of GBP 50: risk neutral.
• Answer below GBP 50: risk averse.
• Answer above GBP 50: risk loving (rare in stable populations).

Definition:

• Loss aversion = tendency to weight losses ~2-2.5x more heavily than equivalent gains.
• Identified by Kahneman + Tversky in their 1979 prospect theory paper.
• The pain of losing GBP 100 ≈ the pleasure of gaining GBP 200-250.

It's asymmetric:

• Equal gains and losses are perceived very differently.
• Reference point matters - what counts as 'gain' or 'loss' depends on starting point.
• Same outcome can feel like gain or loss depending on framing.

It's emotional / behavioural, not rational:

• Rationally, GBP 100 should be GBP 100 whether labelled 'gain' or 'loss'.
• But humans systematically feel losses more than gains.
• This produces predictable + irrational decision patterns.

Measuring loss aversion:

• Standard question: 'I'll flip a coin - heads you lose GBP X, tails you win GBP Y. What's the minimum Y that makes you take the bet?'
• Most people respond Y ≥ 2X.
• Y / X is the loss-aversion ratio (typical 2-2.5).

Pure risk aversion (no loss aversion):

• Prefers diversification across all volatility.
• Treats portfolio gains + losses symmetrically.
• Rebalances rationally regardless of recent outcomes.
• Sells losing positions when fundamentals deteriorate, regardless of original purchase price.

Pure loss aversion (no excess risk aversion):

• Avoids realising losses by holding losing stocks indefinitely.
• Sells winning stocks early (locks in gains, avoids potential losses).
• Reluctant to rebalance because of psychological cost of selling winners.
• Insurance over-purchasing (relief from feared loss is worth more than premium cost).

Combined (most people):

• Risk-averse: avoids extreme volatility.
• Loss-averse: also asymmetrically responds to recent outcomes.
• Result: complex behaviour, often suboptimal.

1. Disposition effect:

• Tendency to sell winners + hold losers.
• Driven by loss aversion (loath to recognise loss).
• Empirical evidence: investors who hold their losing trades 2x longer than winning trades.
• Cost: ~1-3%/year underperformance vs systematic rebalancing.

2. Endowment effect:

• Overvaluing what you own.
• Driven by loss aversion (selling = recognising potential loss of better future appreciation).
• Empirical: people demand 2-3x more to sell something they own than they'd pay to buy it.

3. Reluctance to rebalance:

• Selling appreciated assets feels like 'giving away gains'.
• Buying underperforming asset feels like 'chasing losses'.
• But rebalancing is rational (assuming you believe in your target allocation).
• Cost: failure to rebalance underperforms by ~0.3-0.7%/year.

4. Over-insurance:

• Loss aversion makes us overpay for insurance premiums.
• Average UK car insurance: premium is ~30-50% more than expected claim payout.
• Worth it for risk-averse reasons in some cases (catastrophic loss); but loss aversion may make us over-insure smaller risks.

1. Reframe losses as 'opportunity costs':

• Instead of 'selling at a loss', frame as 'reallocating capital to higher-expected-value asset'.
• Reduces loss-aversion sting.

2. Pre-commit to rules:

• Automatic rebalancing schedule (quarterly).
• Stop-loss rules at fundamental deterioration triggers.
• Pre-commitment removes in-the-moment loss-aversion bias.

3. Use decision frameworks:

• For each decision: 'What would I do if I had no current position?'.
• Removes endowment effect.
• Brings rational analysis back.

4. Diversify your reference points:

• Don't anchor on purchase price.
• Multiple reference points: today's price, 1-year average, fair value, opportunity cost.
• Reduces single-anchor loss aversion.

5. Practice on small-scale decisions:

• Build mental immunity through repeated low-stakes practice.
• Helps when high-stakes decisions arrive.

Risk tolerance:

• Your willingness to take on volatility risk.
• Affected by: age, wealth, income stability, time horizon, dependents.
• Quantified in standard 'aggressive/balanced/conservative' portfolio questionnaires.

Risk aversion:

• The economic concept of preferring certainty.
• Mathematical property of utility function.

Loss aversion:

• The behavioural bias of overweighting losses.
• Empirically-observed psychological phenomenon.

How they interact:

• Someone with high risk tolerance (younger, employed, no dependents) can still be loss averse + make irrational disposition-effect decisions.
• Someone with low risk tolerance (older, retired) should be highly risk averse (rational); their loss aversion makes things worse.