The One Signal Wall Street Can’t Fake
Why would a CEO spend $2 million of their own money buying shares of their own company on the open market?
Think about that for a second. This person already has stock options. Already has a salary. Already has restricted stock units vesting every quarter. They don’t need more exposure to this stock. They’re already overexposed to it.
And yet they walk into the market, pull out their personal checkbook, and buy more.
There’s only one rational explanation. They believe the stock is going higher. And they know things about that company that you and I will never know.
What Counts as Insider Buying
Insider buying is when a corporate officer, director, or major shareholder (anyone holding more than 10% of a company’s stock) purchases shares of that company on the open market using their own money.
This is different from stock option exercises, restricted stock grants, or any other form of compensation-related share acquisition. Those are part of a pay package. They’re planned. They’re expected.
Open-market purchases are voluntary. Nobody made them do it. No compensation committee required it. The insider looked at the current price, decided it was cheap, and bought.
Every time this happens, the insider is required by law to report it to the SEC within two business days by filing a Form 4. This filing is public. Anyone can see it. And that’s what makes insider buying one of the few genuinely useful signals in public markets.
The Asymmetric Information Edge
Here’s the reality of how public markets work. Corporate insiders possess information that outside investors don’t have access to.
They know the sales pipeline. They’ve seen next quarter’s preliminary numbers. They know about the contract that hasn’t been announced yet. They know whether the new product launch is tracking ahead of projections or falling behind.
None of this is “insider trading” in the illegal sense. They’re not trading on material non-public information about a specific event. But they have a general, deep understanding of their company’s trajectory that no analyst report or earnings call can fully replicate.
When an insider buys, they’re making a bet with their own wealth that the market is undervaluing their company. That’s a powerful statement.
Peter Lynch put it simply: “Insiders might sell their shares for any number of reasons, but they buy them for only one: they think the price will rise.”
Buying vs. Selling: An Important Distinction
This is where most people get confused. Insider selling gets the headlines. “CEO dumps $50 million in stock!” It sounds alarming. But insider selling is genuinely ambiguous.
Executives sell for all sorts of mundane reasons. Diversification. Tax planning. Buying a house. Funding a divorce. Paying for their kid’s college. A pre-scheduled 10b5-1 plan that was set up months ago. Selling tells you almost nothing about a company’s prospects.
Insider buying is different. There’s no ambiguity. Nobody buys stock to diversify. Nobody buys stock because they need liquidity. Nobody sets up a scheduled plan to systematically buy more of a stock they think is going down.
Buying is always a bullish signal. Always. The only question is how bullish, and that depends on who’s buying, how much they’re spending, and whether other insiders are doing the same thing.
The Numbers Don’t Lie
Academic research has consistently shown that insider buying outperforms the broader market.
A study published in the Journal of Finance found that stocks with insider purchases outperformed the market by an average of 6% over the following 12 months. Another study from researchers at Wharton found that the heaviest insider buying (top decile by dollar amount) generated excess returns of 8.9% annually.
More recent data backs this up. From 2010 to 2023, stocks with significant CEO or CFO open-market purchases (over $100,000) outperformed the S&P 500 by a median of 1.7% to 2.8% across 30-day, 90-day, and one-year windows. That’s after accounting for the overall market trend.
The signal gets even stronger during periods of market stress. When markets are falling and insiders start buying aggressively, the subsequent returns tend to be even higher. It makes sense. Insiders buying during a panic means they see value that the market, driven by fear, is ignoring.
What This Means for You
Insider buying isn’t a crystal ball. It’s not a guarantee. Some insider purchases lead nowhere. Sometimes management is just wrong about their own company.
But as a starting point for research, there is no better public signal. When a CEO puts a million dollars on the table, they are telling you something. Whether you listen is up to you.
The real skill is learning to filter. Which insiders matter most. How much money is significant. Whether the timing aligns with broader momentum. That’s what separates the investors who use insider data effectively from the ones who chase every Form 4 that hits EDGAR.
We’ll get into all of that in the articles ahead.