Behavioral Investing
Psychology of investing and how to avoid the mistakes that cost you money.
Why Behavior Matters
The behavior gap: The average investor significantly underperforms the investments they own.
| Period | S&P 500 Return | Average Investor Return |
|---|---|---|
| 20-year (through 2022) | 9.8% | 5.8% |
The ~4% gap comes from behavior: buying high, selling low, chasing performance.
Cognitive Biases in Investing
Loss Aversion
Losses hurt twice as much as equivalent gains feel good.
| Impact | Result |
|---|---|
| Hold losers too long | Hope they'll come back |
| Sell winners too early | Lock in gains to avoid potential loss |
| Avoid stocks after losses | Miss recovery |
| Check portfolio too often | Focus on daily losses |
Fix: Think in total return over years, not daily fluctuations.
Overconfidence
We think we're better at investing than we are.
| Belief | Reality |
|---|---|
| "I can pick winning stocks" | 80% of pros underperform indexes |
| "I know when to get in/out" | Market timing fails consistently |
| "This time is different" | Patterns repeat |
| "My research gives me an edge" | Information is priced in |
Fix: Accept that you can't beat the market consistently. Use index funds.
Recency Bias
We assume recent trends will continue.
| When Market Is... | We Assume... | Then... |
|---|---|---|
| Rising | It will keep rising | Buy at the top |
| Falling | It will keep falling | Sell at the bottom |
Fix: Remember that markets are cyclical. Mean reversion is real.
Anchoring
We fixate on arbitrary reference points.
| Anchor | Problem |
|---|---|
| Purchase price | "I'll sell when I break even" |
| Past high | "It was $200, now it's $150, it's cheap!" |
| Round numbers | "I'll buy when it hits $100" |
Fix: Evaluate investments on current fundamentals, not past prices.
Herd Mentality
We follow the crowd.
| Crowd Action | Your Impulse | Likely Outcome |
|---|---|---|
| Everyone buying | "I should buy too" | Buying near top |
| Everyone selling | "I should get out" | Selling near bottom |
| "Everyone's doing it" | FOMO | Poor entry point |
Fix: Be skeptical when everyone agrees. Best opportunities often feel wrong.
Confirmation Bias
We seek information that confirms what we already believe.
| If You Own... | You'll Notice... | You'll Ignore... |
|---|---|---|
| Tech stocks | Bullish tech articles | Tech concerns |
| Gold | Inflation warnings | Deflation arguments |
| Crypto | Adoption stories | Regulatory risks |
Fix: Actively seek opposing views. Ask "why might I be wrong?"
Emotional Traps
Fear and Greed Cycle
| Market Phase | Emotion | Typical Action | Should Do |
|---|---|---|---|
| Bottom | Despair, capitulation | Sell everything | Buy |
| Recovery | Skepticism | Stay out | Stay invested |
| Bull market | Optimism | Start buying | Already invested |
| Peak | Euphoria, greed | Buy aggressively | Rebalance |
| Decline | Denial, fear | Hold, then panic | Hold |
| Crash | Panic | Sell at bottom | Buy more |
The crowd is almost always wrong at extremes.
FOMO (Fear of Missing Out)
Triggers:
- Friends making money
- Stocks at all-time highs
- Hot tips and success stories
- Parabolic price moves
Result: Buying after big moves, just before corrections.
Fix: Stick to your allocation regardless of what's "hot."
Panic Selling
During market crashes:
| What Feels Right | What Works |
|---|---|
| Sell and wait for bottom | Stay invested |
| Move to cash for safety | Miss recovery |
| "I'll get back in later" | Buy back higher |
Historical perspective:
- Markets have always recovered
- Best days often follow worst days
- Being out for 10 best days destroys returns
Regret Avoidance
| Scenario | Feeling | Bad Decision |
|---|---|---|
| Sold, price went up | Regret | Avoid selling winners |
| Bought, price went down | Regret | Avoid buying |
| Didn't buy, price went up | Regret | Buy after rise |
Fix: Accept that some decisions won't work out. Focus on process, not outcomes.
Behavioral Defenses
Automation
Remove yourself from the process:
- Automatic contributions
- Auto-rebalancing
- Target-date funds
- Don't hold cash waiting for "right time"
Investment Policy Statement
Write down your plan:
| Element | Your Answer |
|---|---|
| Goals | Retirement at 60, kids' education |
| Allocation | 70% stocks, 30% bonds |
| Contributions | $1,000/month |
| Rebalancing | Annually, or at 5% drift |
| When I'll sell | Only to rebalance or meet goals |
During volatility, read your policy. It's past-you telling present-you what to do.
Limit Information
| Less of... | More of... |
|---|---|
| Daily market news | Quarterly reviews |
| Stock tips | Index funds |
| Checking portfolio | Automation |
| Short-term noise | Long-term perspective |
Checking more often → more stress → worse decisions
Long-Term Perspective
| Time Horizon | Probability of Positive Return (stocks) |
|---|---|
| 1 day | 53% |
| 1 month | 63% |
| 1 year | 75% |
| 5 years | 88% |
| 10 years | 95% |
| 20 years | 100% (historically) |
The longer you hold, the more certain positive returns become.
Rules to Follow
Pre-Commitment Rules
Decide in advance:
| Rule | Purpose |
|---|---|
| "I won't check more than monthly" | Reduce noise |
| "I won't sell during declines" | Avoid panic |
| "I'll only rebalance annually" | Reduce trading |
| "I'll never buy on a tip" | Avoid speculation |
| "I'll ignore predictions" | Reduce noise |
Cooling-Off Periods
Before any trade:
- Wait 48 hours
- Write down why you're doing it
- Ask "what would I tell a friend to do?"
The 10-10-10 Rule
Before acting, ask:
- How will I feel in 10 minutes?
- How will I feel in 10 months?
- How will I feel in 10 years?
Market Perspectives
On Market Crashes
| Fear | Reality |
|---|---|
| "It's different this time" | It never is |
| "It will never recover" | It always has |
| "I need to get out" | Selling locks in losses |
| "I'll know when to get back in" | You won't |
Every crash feels like the end. None have been.
On Bull Markets
| Greed | Reality |
|---|---|
| "It can only go up" | Corrections are inevitable |
| "I should put in more" | Stick to allocation |
| "This time is different" | It never is |
| "I'm a genius" | Market is making everyone rich |
Historical Context
| Event | Drop | Recovery Time |
|---|---|---|
| 2020 COVID crash | -34% | 5 months |
| 2008 Financial crisis | -57% | 4 years |
| 2000 Dot-com | -49% | 7 years |
| 1987 Black Monday | -22% (one day) | 2 years |
| 1929 Great Depression | -89% | 25 years |
Average bear market: -35%, lasts 14 months Average bull market: +180%, lasts 5+ years
Signs You're Making Emotional Decisions
- Checking portfolio multiple times per day
- Losing sleep over investments
- Making changes based on news
- Feeling euphoria or despair about markets
- Talking about stock tips at parties
- "This time is different" thinking
Key Takeaways
- You are your worst enemy - Behavior costs more than fees
- Automate everything - Remove emotion from the process
- Don't watch the news - It's designed to provoke, not inform
- Stick to the plan - Written policy beats impulse
- Think long-term - Zoom out when scared
- Boring wins - Excitement in investing is costly
- Accept imperfection - Some decisions will feel wrong