Last spring, Sarah, a 32-year-old graphic designer in Austin, sat across from me at a café, scrolling through her investment app with a tight frown. “My friend Jake made $3,000 on that AI stock in two weeks,” she said, tapping a bright green line on the screen. “I finally bought in when it hit $80… now it’s $45.” She paused, voice softening. “I just didn’t want to miss out. Everyone on my finance Discord was talking about it like it was free money.”
Sarah’s story isn’t unique. It’s a playbook written by two powerful forces in behavioral finance—FOMO (fear of missing out) and mental accounting—that push even thoughtful people into the “high buy, low sell” trap. These aren’t flaws in character; they’re wired into how we process risk, reward, and social proof. Understanding them doesn’t just explain why we chase hot stocks—it helps us recognize when our brains are leading us astray.
FOMO, in financial terms, is the urge to jump into an investment because others seem to be profiting from it, even when we lack evidence that the gains will last. It’s driven by a primal need to belong: when we see peers posting about their “wins” on social media, or online communities buzzing about a “next big thing,” our brains interpret missing out as a loss—sometimes even a bigger loss than losing money on a bad trade. A 2022 study of retail investors found that those who reported high FOMO were 2.7 times more likely to buy stocks at their 52-week highs, and 3.1 times more likely to sell those same stocks after a 20% drop. Sarah fit that pattern: she didn’t research the AI company’s revenue or competition—she bought because Jake did, and because the Discord chat made her feel like she was falling behind.
Then there’s mental accounting, the tendency to treat money from different sources (or for different goals) as separate “buckets,” even though a dollar is always a dollar. For Sarah, the money she used to buy the AI stock came from a year-end bonus—“extra cash,” she called it—so she felt less cautious than she would have with her regular savings. “It didn’t feel like the same money I use for rent,” she said. That’s mental accounting at work: we often take bigger risks with “windfalls” because we don’t attach the same emotional weight to them as we do to money we earned through daily work. This bias makes us more likely to chase hot stocks with “extra” cash, ignoring the fact that even bonus money can vanish if the investment tanks.
Together, these biases create a perfect storm for “high buy, low sell.” FOMO pulls us in when prices are already inflated (everyone else is buying, so we do too), and mental accounting lowers our guard (it’s “fun money,” so what’s the harm?). Then, when the stock drops—because hot trends cool, or fundamentals don’t match the hype—fear kicks in. We realize we didn’t understand the investment, and because we see that money as “extra,” we’re quick to sell to cut our losses, locking in a downturn that might have been temporary. Sarah sold her AI stock at $45 not because she analyzed the company’s prospects, but because she couldn’t stand watching that “bonus money” disappear.
What makes this trap so tricky is that it doesn’t feel like a mistake at the time. It feels like joining the crowd, like seizing an opportunity, like being smart with “extra” cash. But behavioral finance tells us that the crowd is often wrong at the extremes—too optimistic when prices are high, too pessimistic when they’re low. Sarah later told me she’d started using an investment journal to write down why she wanted to buy a stock before hitting “confirm”—not just who was talking about it, but what the company did, and whether it fit her long-term goals. “I still get FOMO,” she said, “but now I pause. Is this me investing, or just me scared to miss out?”
That pause is the first step to avoiding the trap. We can’t eliminate our biases—they’re part of being human—but we can learn to notice them. When a hot stock crosses your radar, ask: Am I buying this because of data, or because of what others are doing? Is this money coming from a “fun” bucket, or does it matter if I lose it? These questions don’t give easy answers, but they turn impulsive decisions into thoughtful ones. And for people like Sarah—people who just want to grow their money without feeling like they’re gambling—that’s the difference between chasing trends and building something lasting.
