How to Spot Insider Buying Signals That Actually Matter

Why most insider activity is noise

Insider buying has a good reputation, and for good reason: the people who run a company understand it better than any outside analyst, and when they put their own money into the stock they are betting on themselves. But the raw insider feed is mostly compensation. In the 12 months to September 2026, grants, option exercises and tax withholding made up more than half of all Form 4 transactions SignalX parsed, and open-market purchases only 6.8%.

If the codes are new to you, start with our guide to Form 4 transaction codes. This guide is about what comes next: deciding which purchases actually matter.

The six-question test

The more of these that are a yes, the stronger the signal.

1. 1

   Was it an open-market purchase (code P)?

   Only voluntary buys signal conviction. Grants and option exercises do not.

2. 2

   Did several insiders buy together?

   A cluster of independent buyers is far stronger than one.

3. 3

   Is the buy large relative to their stake?

   A director doubling their position means more than a token purchase.

4. 4

   Who bought: the CEO or CFO?

   The people closest to the numbers carry the most signal.

5. 5

   Did they buy into weakness?

   Buying after a selloff says they think the market is wrong.

6. 6

   Was it discretionary, not a 10b5-1 plan?

   Scheduled trades were decided months earlier.

Cluster buying beats a lone buyer

A single purchase can mean many things. A cluster, where several officers and directors buy within the same short window, is much harder to explain away. Independent people acting the same way at the same time suggests they are responding to the same view of the business.

Here is a real example from SignalX data. Between September 8 and October 1, 2026, five GameStop insiders bought shares on the open market on six separate trading days, about $59.3 million in total. Chairman and CEO Ryan Cohen accounted for most of it, and four directors added their own smaller purchases.

SignalX defines a cluster as three or more officers or directors buying at least $250,000 in total, and it excludes same-day purchases at one price, which usually reflect a company share offering rather than independent decisions. By that definition there were 76 clusters across the market in the 90 days to October 2026.

Size relative to the person, not the company

A $200,000 purchase sounds large, but what it means depends on who made it. For a CEO with tens of millions in stock it may be a rounding error. For a director, it might be a serious personal commitment. Judge a buy against the insider's existing holdings, shown on the Form 4 as shares owned after the transaction, and against their pay. A purchase that meaningfully increases what an insider has at stake is the one that signals conviction.

Who is buying

Not all insiders are equal. The CEO and CFO sit closest to the financial reality of the business, so their purchases carry more weight than those of a non-executive director with less day-to-day visibility. A CFO buying is particularly watched, because that is the person who knows exactly how the quarter is shaping up. In the 90 days to October 2026, SignalX recorded 541 Form 4 filings with an open-market purchase by a CEO.

Buying into weakness

Timing and price add context. An insider buying after the stock has fallen is saying the market has overreacted. Buying near highs is less contrarian. The strongest version of the signal is a cluster of executives buying meaningful amounts into a selloff, on their own initiative rather than a preset schedule.

What buying cannot tell you

Insiders can be wrong. They are optimistic about their own companies almost by definition, and buying is a sign of belief, not a guarantee. Treat it as one input that raises a company's priority for your own research. And remember the asymmetry: buying is a cleaner signal than selling, because there are many innocent reasons to sell. Our guide to insider selling covers when sales do matter.

How SignalX scores insider buying

SignalX reads every Form 4 on EDGAR, filters out bond and option rows with impossible prices, and builds the views that answer these questions: cluster buys, CEO and CFO purchases, repeat buyers who keep adding on separate days, and net buying by company. It re-scores them every day and puts the strongest on the Today board.