How to research insider buying without treating it as a buy signal
When an officer, director, or 10% owner of a US public company trades their own company's stock, the trade must be disclosed to the SEC, usually on Form 4 within two business days. An insider buying screener collects those filings and shows you where insiders have recently been buying.
That is genuinely useful information. It is also one of the most over-interpreted datasets in retail investing. The filings tell you what happened. They do not tell you why, and they are not a buy list.
What the filings actually say
Insider disclosure comes on SEC Forms 3, 4, and 5. Form 4 is the one that matters for recent activity, and its transaction codes carry the meaning.
Code P is an open-market purchase: the insider spent their own money at market prices. Code S is an open-market sale. Other codes cover option exercises, awards, gifts, and plan transactions. A screener that lumps these together will call a routine stock grant "insider activity," which is technically true and analytically useless.
Open-market purchases are the interesting class, because they are voluntary and costly. Sales are much weaker evidence in the other direction. Insiders sell for taxes, diversification, house purchases, and scheduled 10b5-1 plans, so a sale often says nothing about their view of the business.
Why buying still is not a signal
Three reasons to keep your skepticism.
Insiders are early and often wrong on timing. A director buying after a 40% decline may be catching a falling business, not a bottom.
Size matters more than occurrence. A $25,000 purchase by an executive earning millions is a gesture. A purchase that is large relative to the insider's existing stake and compensation is information.
The disclosure is lagged and the context is missing. You see the trade days after it happened, and you do not see the alternatives the insider weighed.
The pattern researchers tend to respect most is cluster buying: several different insiders making open-market purchases in the same window. One conviction is noise. Five separate convictions are worth a look.
A workflow that uses it properly
Start wide, then narrow by evidence.
First, screen for recent open-market buying: stocks with recent open-market insider buying. Each company in the result shows dated activity drawn from the filings.
Second, open the company's insider history and read the detail: who bought, at what size, purchase or plan transaction, one insider or several. Every covered company on stocks-llm has an insider trades page linked from its profile, with each row tied to the original SEC filing.
Third, treat the buy as a question, not an answer. What changed at the business around the purchase date? Check the recent filings, margins, and guidance. Insider buying earns a company a place on your research list. The fundamentals decide whether it stays there.
The insider buying screener page describes how the screen defines its terms.
Limits worth stating plainly
Insider data covers disclosed US trades by covered insiders, arriving on a legal delay. It cannot capture intent, and a screener cannot know whether a purchase reflects insight or obligation or public relations. Companies outside the catalog are absent from results for coverage reasons, not because insiders are inactive there.
stocks-llm is for informational research only, not financial advice. Insider disclosures are not recommendations. Verify material information independently against primary sources before making an investment decision.