You see it happen all the time. A company reports earnings. The stock gets crushed — down 10%, 15%, even 20% in a single day. You assume the worst. The company must be in trouble, right?

Then you check the insider transaction filings. And there it is: the CEO just bought $1 million worth of shares.

It seems contradictory. Why would someone with the most information about a company buy stock right after bad news sent the price tumbling?

The answer reveals one of the most powerful signals in the stock market — and it’s not as complicated as you might think.

The Classic Pattern: Bad News, Then Insider Buying

Let’s look at a real example.

In December 2025, Nike (NKE) reported earnings that looked terrible on the surface. The stock plunged 11% in a single day. China sales had dropped 17% year-over-year. Management warned about $1.5 billion in annualized tariff headwinds. Analysts slashed price targets across the board — 17 firms cut their targets on December 19th alone .

It was exactly the kind of news that makes ordinary investors hit the sell button.

But here’s what happened next. On December 22nd — just days after the crash — Apple CEO Tim Cook, who sits on Nike’s board, bought 50,000 shares worth approximately $3 million at prices near $58 . Fellow director Robert Swan also acquired $500,000 in shares the same day .

The stock rallied 4.6% the next day .

This isn’t an isolated incident. It’s a pattern that plays out regularly across the market — and understanding it could change how you react to bad news.

Why Insiders Buy After Bad Earnings

There’s a simple reason executives buy stock after their company’s shares get hammered: they believe the market is overreacting.

When you dig into why stocks drop after earnings, the reason is often not that the company is broken. It’s that the company’s results missed Wall Street’s expectations — expectations that were often unrealistic to begin with.

Consider Nike’s situation. Yes, China sales were down. But Nike actually beat earnings estimates for the quarter, reporting $0.53 per share versus the $0.37 analysts expected . Revenue hit $12.4 billion. The company posted its best Black Friday ever on Nike.com, with high double-digit growth in running and kids categories .

The market focused on the China weakness and the tariff warning. Insiders like Tim Cook focused on the underlying business strength and the fact that the stock was now trading at multi-year lows.

The same dynamic played out with O-I Glass in August 2025. The stock dropped more than 15% after earnings, even though the company reported earnings of $0.53 per share — a solid beat over consensus — with revenues steady year-over-year . The CFO and General Counsel both bought stock as the price fell, recognizing that the market’s reaction was disconnected from the company’s actual performance .

What the Research Says About Insider Buying

The data backs this up. When insiders — especially C-suite executives — buy shares after a price decline, it’s often a sign that the stock is undervalued.

A proprietary signal called “Cessation of Selling” tracks when insiders who normally sell their shares suddenly stop. VerityData’s research shows this pattern often precedes significant stock appreciation .

Take Microsoft as an example. The company had insider sales in every quarter for more than 15 years. Then in Q1 2025, the pattern stopped. The stock had drifted lower after earnings, yet none of the usual sellers participated — a collective decision to sit it out .

Within weeks, shares rose sharply. By the time insiders resumed selling in the next window, the stock was 15–20% higher — and eventually more than 40% above the point where selling had paused .

As Ben Silverman, VerityData’s Director of Research, put it: “At a lot of companies, when insiders who regularly sold stopped selling, it was an identifier that insiders thought that the stock was undervalued” .

When Insider Buying Is a Warning Sign

Not all insider buying is created equal. Sometimes, it’s actually a red flag.

There are cases where executives buy stock not because they believe in the company’s future, but because they’re trying to prop up the stock price artificially — or because they have information the public doesn’t that would make the stock look even worse if revealed.

The Shijiazhuang Pharmaceutical Group case offers a cautionary tale. An executive director purchased nearly 100 million yuan worth of shares just before a major restructuring announcement — trading on inside information . The regulator fined him 5 million yuan, and he was forced to resign .

That’s not confident buying. That’s illegal insider trading.

Similarly, when Hainan Huatie’s stock collapsed after a $5 billion computing services contract fell apart, shareholders announced plans to buy up to $48 million in shares . But the company was also under investigation by securities regulators for potential信息披露 violations . Was the buying a sign of confidence — or an attempt to stabilize a sinking ship?

The key difference is transparency. When insiders buy after transparent, honest earnings reports that simply missed expectations, it’s usually a positive signal. When they buy while hiding bad news or facing regulatory scrutiny, it’s a danger sign.

How to Evaluate Insider Buying for Yourself

If you see an insider purchase after a stock drop, here’s what to check before getting excited.

Was the purchase open-market or part of a compensation plan? Open-market purchases — where executives use their own cash — are much more meaningful than stock grants or option exercises.

How large is the purchase relative to their compensation? A $100,000 purchase means something different to a CEO making $2 million a year versus one making $20 million.

Are multiple insiders buying? One executive buying is interesting. The CFO, COO, and several directors all buying at the same time is a much stronger signal.

What was the reason for the drop? If the drop came from a temporary, fixable problem (like a supply chain hiccup or a one-time charge), insider buying is more meaningful. If it came from a structural problem (like losing a major customer or facing regulatory action), be more cautious.

Check the valuation. Insiders buying a stock that already trades at 10 times earnings is different from insiders buying a stock at 50 times earnings. The former has more room for error.

Real-World Examples: What the Numbers Show

Let’s look at some actual data from 2025.

Eastman Chemical (EMN): The stock fell 24% in 2025 due to tariff concerns. The CEO bought about $502,000 of shares, and the CFO bought about $252,000. Several other executives bought the same day . The stock trades at about nine times earnings and less than one times revenue — far below its typical multiples .

United Parcel Service (UPS): Shares fell more than 31% in 2025 due to competition from Amazon. The CEO spent just over $1 million to add to her holdings. Two directors also bought shares in July and August . The stock trades for less than 13 times earnings with a standout return on equity above 34% .

Portillo‘s (PTLO): The stock dropped 30% in a month after revenue growth disappointed. The CFO, Senior Counsel, and one director all made large purchases . The brand has a cult-like following and is expanding nationally — a fixable growth challenge, not a broken business.

In each case, insiders were buying after significant price drops. In each case, the underlying business remained fundamentally sound.

What This Means for You

Here’s the practical takeaway.

Don’t panic sell on bad earnings. Wall Street’s reaction to earnings is often emotional and short-term. The people who know the company best — its own executives — are sometimes buying when everyone else is selling.

Watch for clusters of insider buying. One insider buying could be anything. Multiple insiders buying around the same time — especially after a price drop — is worth paying attention to.

Do your own homework. Insider buying is a signal, not a guarantee. It should be one factor in your research, not the only factor.

Be patient. Insiders typically think in years, not days or weeks. The Microsoft example showed shares rising 40% over months after insiders signaled confidence . This isn’t a get-rich-quick signal.

The Bottom Line

When a stock drops 20% after earnings and the CEO buys shares, it’s not a contradiction. It’s a reflection of two different time horizons.

The market is focused on the next quarter. The CEO is focused on the next three to five years.

The market is reacting to a missed number. The CEO is looking at the underlying business — the customers, the products, the balance sheet, the long-term strategy.

Neither is necessarily wrong. But understanding the difference between short-term noise and long-term value is one of the most important skills an investor can develop.

And sometimes, the best signal of that long-term value comes from the people who know it best — buying when no one else wants to.

Why Did This Stock Drop 20% After Earnings — But Its CEO Just Bought Shares?