Why Smart Investors Make Crazy Decisions — Alex Edmans | Ideas Lab | Ep.54
Alex Edmans discusses how sentiment and behavioral biases can shape market prices, from World Cup results and Spotify playlists to investors' responses to losses, winners, and frequent portfolio checks. He argues that individual investors may find an edge through patience or overlooked information, while active managers face fee, benchmark, and career pressures. The discussion also examines momentum's potential and crash risks, ways to test investment theses, and Edmans's view that a reasonable equity premium is roughly 3% to 4%.
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Alex Edmans says market prices can move with investor sentiment: a country's World Cup elimination has been followed by about a 0.5% market decline, and happier Spotify playlists have correlated with higher stock prices and lower government bond prices. He suggests optimism may shift money toward equities and away from safer assets such as UK government bonds.
Edmans argues that an investor's potential advantage may be the ability to wait through downturns rather than to call the bottom: he cites buying equities during the 2009 crisis and waiting five or 10 years for recovery. Cambridge University's 2009 investment illustrates both the potential payoff and the financing cost of that approach: about £10 million of debt grew to £15 million over 10 years, while the equity investment reached £30 million.
Edmans says investment specialization can center on a repeatable information edge rather than one industry, but a fund's prospects are unclear if it cannot identify that edge. As an example, he describes a fund investing $20 million in Turkey's only listed hazelnut processor after frost destroyed a third of the crop in April 2025; the company's value rose 40% when the shortage reached headlines.
Edmans argues that active managers should outperform their passive benchmarks to justify fees of 75 basis points versus five basis points for a passive fund, and that benchmark-hugging can undermine the case for active management. He says career risk may keep managers in AI stocks even if they believe there is a bubble; research he cites links higher active share with outperformance, but he cautions that active positions should reflect the manager's claimed expertise rather than active share becoming a target on its own.
Edmans explains that momentum can exploit investor underreaction to news, including confirmation bias, and says it has typically outperformed across regions and asset classes; the host notes that momentum can also suffer crashes that erase years of gains. Edmans says a high VIX can be a useful but imperfect warning because momentum typically underperforms when volatility is high, while crashes can still occur unexpectedly.
MARKETS
“To put some numbers on it, it's about half a percent even when you control for the broader world market movement…”—
“And what we showed was that was also significantly correlated with stock prices…”—
“But instead, your edge comes from a different source, which is exactly what you've identified, Kevin, which may well be the ability to be free to be able to play…”—
Introduction and Alex Edmans’ new book The Madness of Markets
Edmans introduces his book and explains that market prices can reflect investor psychology as well as fundamentals, motivating his research into how sentiment shapes financial decisions.
How football results can move stock markets
Research on World Cup outcomes finds that national mood can move stock markets: markets often fall after a country is eliminated, while Brazil’s 7–1 defeat produced a different response tied to political expectations.
What Spotify playlists can tell us about investor sentiment
Spotify listening data offers an aggregate signal of national mood; the emotional tone of popular music correlates with stock prices and, in the opposite direction, government bond prices.
Why individual investors may have an advantage over professionals
Individuals may have an advantage over professional managers because they can wait through volatility, invest on long horizons, and avoid client withdrawals and career pressures.
Specialists, generalists and finding your investing edge
Investors should identify where their genuine expertise lies. Expertise can be sector-specific or thematic, while overlooked local information—such as Turkey’s hazelnut crop—can create opportunities.
When benchmarks make active managers too conservative
Benchmarks help clients compare active managers with low-cost index funds, but career concerns can make managers hug benchmarks. Active share may indicate conviction when it reflects a manager’s stated expertise.
Risk, alpha and the equity premium puzzle
Edmans distinguishes risk-adjusted alpha from raw returns and argues that a reasonable equity premium is roughly 3% to 4%; skilled managers may add value by accessing unusually attractive markets.
Why momentum works and when it crashes
Momentum can exploit investors’ tendency to underreact to news, but it can crash sharply. High volatility may warn of trouble, while professional career risk can keep managers from pursuing the strategy.
Where individual investors can exploit overlooked opportunities
Small, lightly covered companies may offer stronger momentum opportunities because information is easier to overlook and large institutions face liquidity constraints that individual investors can avoid.
How round numbers influence buying and selling decisions
Investors often cluster orders around round prices, making those levels harder to trade through; placing buy or sell limits just beyond them can improve the chance of execution.
The disposition effect and why investors hold onto losers
The disposition effect leads investors to hold losing stocks and sell winners too soon. Rolling a losing position into another investment can make it easier to exit without feeling that the whole investment effort has ended.
Three practical ways to make better investment decisions
Edmans recommends checking portfolios less often, testing the case against a desired trade, and accounting for one’s mood to reduce emotional decisions and stale-information trading.
Why writing down your investment thesis matters
Writing down both the positive and negative cases, along with decision criteria, makes an investment thesis more deliberate and allows investors to assess later whether the original reasoning held up.
Outsourcing the ugly decisions
Delegating difficult sell decisions can help overcome reluctance to admit a mistake. Edmans uses outside critics to identify weak sections in his own writing, applying the principle beyond investing.
AI, bubbles and the big market delusion
The big market delusion occurs when excitement makes investors value an entire emerging industry as though every company will win. Edmans sees a similar risk in AI and trimmed his exposure after strong gains.
Closing thoughts and where to find the book
Edmans and the host close by recommending the book and thanking listeners; the episode ends with the show’s standard disclaimer about investment risk and informational content.
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Important Disclaimers
Not Investment Advice: For education only — not financial, tax or legal advice.
AI-Generated: Made by AI from source transcripts and may contain errors.
No Guarantees: Past performance does not predict future results; investing carries risk.
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