Latest / Behavioral Economics with Fexingo: Decision Making, Bias, and How People Really Spend / How One Number Creates a Self-Fulfilling Prediction
Transcript
- Lucas: There's a line from the philosopher Karl Popper that I think about a lot: 'The prophecy will shape the event.' He was writing about history, but it applies just as cleanly to markets. Luna: You're talking about the self-fulfilling prophecy — if enough people believe a bank is about to fail, they'll rush to withdraw their money, and the bank actually fails. Lucas: Exactly. But I want to get more specific today — not just the broad idea, but a concrete experimental finding from the University of Chicago about how expectations change actual financial outcomes. Luna: Okay, I'm hooked. What did they do? Lucas: Researchers gave two groups of students real money to invest. Both groups got the same portfolio — same stocks, same weights, same everything. But they told one group the portfolio had been designed by a top-performing expert and had generated twelve percent returns the previous year. The other group was told the portfolio was average — maybe six percent. Luna: And both portfolios were actually identical? Lucas: Identical. Same assets, same allocation. The only difference was the label. Over the trading period, the group that believed they held the high-performing portfolio earned significantly higher returns. Not because they made different trades — they didn't. But because their belief altered their behavior: they held positions longer, they didn't panic-sell during small dips, and they rebalanced more confidently. Luna: So the label literally created a better outcome. That's wild. Lucas: It's the placebo effect applied to finance. And it's not just a lab curiosity. I think we see it in how corporate guidance works. When a CEO announces confident forward-looking statements, even if the numbers aren't dramatic, the stock often rises. The belief itself becomes a driver. Luna: But is that rational? I mean, if the guidance is just talk, should the market really react? Lucas: That's the question. One reading is that confident guidance signals real inside information — the CEO knows something we don't. But there's also a pure expectations effect: if investors believe the company will perform well, they buy the stock, which lowers the cost of capital, which makes it easier for the company to invest, which actually improves performance. The belief becomes a causal factor. Luna: It's a feedback loop. Belief shapes action, action shapes outcome, outcome confirms belief. Lucas: Right. And this gets especially interesting when you think about how long the effect can last. In the Chicago experiment, the return gap persisted for the entire trading period — weeks. It wasn't just a one-day pop. Luna: So it's not just noise that reverts. Expectations can compound. Lucas: That's the worrying part for anyone trying to be a disciplined investor. Because if you start from a position of pessimism — maybe you bought a stock that's been written off by analysts — your own behavior can lock in underperformance. You sell too early, you second-guess every hold, you miss the recovery. Luna: You're describing a kind of behavioral poverty trap. Lucas: Exactly. And it's not just individuals. There's a famous study by Paul Slovic and colleagues from the 1970s where they showed professional stockbrokers a set of companies' earnings data and asked them to predict future performance. But they manipulated the company names — some were labeled as well-known successful firms, others as struggling. The brokers' predictions were systematically biased by the label, even when the underlying data was the same. Luna: Even professionals? That's sobering. Lucas: It is. And it raises a deeper question about how much of what we call 'skill' in investing is actually just the self-fulfilling consequence of initial expectations. Luna: Before we go further, I want to say — if this episode made something click for you, honestly, if it was worth a coffee, that's the link: buy me a coffee dot com slash fexingo. Lucas: Yeah, listener support is what keeps this show ad-free and independent. No pressure, just if it hit home. Luna: Buy me a coffee dot com slash fexingo. Okay, back to expectations. Lucas: So the question becomes: can you break the cycle? If you know you're prone to expectations bias, can you counteract it? Luna: Is there a known strategy that works? Lucas: One approach is to seek out dissenting information deliberately. If you own a stock everyone loves, force yourself to read the short-seller report. If you're pessimistic about a sector, find the bull case. The Chicago experiment suggests that simply being aware of the label isn't enough — you have to actively override the emotional response. Luna: But that takes discipline. Most people don't want to read things that challenge their narrative. Lucas: That's the whole problem. Confirmation bias is the engine that drives the expectations effect. If you only look for evidence that supports your initial belief, you never correct. Luna: There's also a moral hazard angle here. If CEOs know that confident guidance lifts the stock regardless of reality, they have an incentive to be overly optimistic. And when reality hits, the crash is worse. Lucas: That's a real risk. The SEC actually regulates forward-looking statements for this reason — they have to be accompanied by meaningful cautionary language. But the expectations effect operates below the level of explicit claims. It's in tone, body language, the way a CEO answers a question. Luna: So it's almost impossible to regulate. Lucas: Pretty much. And that's why I think the most practical takeaway is for individual investors: recognize that your own expectations are a variable you can control. If you find yourself feeling overly pessimistic about a holding, ask yourself whether the evidence supports that feeling or whether you're just caught in a negative expectation loop. Luna: It's like being your own behavioral coach. Lucas: Exactly. And there's actually some experimental evidence that this works. Researchers at Yale found that investors who wrote down three reasons their portfolio might perform better than expected — even if they didn't fully believe them — subsequently made more patient, higher-returning decisions. The act of constructing a positive narrative changed their behavior. Luna: So faking it until you make it might actually have a financial payoff. Lucas: In a narrow sense, yes. But I'd be careful — you don't want to become irrationally exuberant. The goal isn't blind optimism. It's calibrating your expectations to avoid self-defeating pessimism. Luna: That strikes me as a really useful lens for thinking about the current market environment. We're in mid-2026, and there's a lot of noise about recession, about AI hype fatigue, about geopolitics. Every investor is swimming in expectations. Lucas: And those expectations are shaping behavior in real time. If everyone expects a downturn, they cut spending, they sell stocks, and in doing so, they may actually create the downturn they feared. That's the Popper prophecy at scale. Luna: So how do you resist that as an investor? Lucas: I think the key is to separate your analysis from the market's mood. Look at fundamental metrics — cash flow, margins, competitive position — and try to ignore the narrative. But that's much easier said than done. Luna: Because the narrative is what drives prices in the short term. Lucas: Exactly. And that's the paradox: if you completely ignore expectations, you might miss important information about what other market participants believe. But if you overweight them, you become a victim of the herd. Luna: It's a tightrope. Lucas: It is. But I think the most durable insight from today is this: expectations are not just passive reflections of reality. They are active inputs that shape reality. And once you see that, you start to notice it everywhere — in product launches, in earnings calls, even in how you talk about your own career. Luna: That's a good note to end on. If you can shift your own expectations, you might shift your outcomes. Lucas: And if you can do that with awareness, without falling into delusion, that's a genuine skill.