Short answer first. When several insiders at the same company buy in the same window, the filings stop being housekeeping and start being a signal, and our database can count how rare that is: 532 cluster buy filings, spread across just 56 tickers, out of 1,890 insider purchases in total. Most companies never produce one. A handful produce them again and again.
The cluster census
| Measure | Count |
|---|---|
| Cluster buy filings in the database | 532 |
| Tickers with at least one cluster | 56 |
| Share of all insider buys that are cluster buys | 532 of 1,890 (28%) |
| Largest single-ticker cluster count | 51 filings (WVVI) |
Our explainer on what cluster buys are covers the definition (three or more insiders buying inside a short window); this page is the census behind it. The concentration is the story: the top five tickers account for 194 of the 532 filings, and the leaders are small companies, a winery, a regional gas utility, community banks, where a board's worth of insiders buying together is a meaningful fraction of the float changing hands.
Where the clusters pile up
How to use the census: a cluster is a starting point, not a conclusion. Check whether the purchases were open-market buys or option exercises recorded in the same week, whether the same insiders were selling something else at the same time, and whether the cluster repeats in a later quarter. The filings themselves answer the first two questions. Only time answers the third, and the clusters that repeat are the ones this database makes impossible to miss.
Taiwan Semiconductor is the exception that proves the pattern: a mega-cap where 31 cluster filings say less about conviction per filing, because the insider base is enormous, than the same count would at a small bank. Read cluster counts against company size, and treat a repeat cluster at a small company as the strongest version of the signal this database produces. The trackers that flag clusters in real time are compared in our cluster tracker roundup.
Sources: hub form modeled on Nasdaq, Earnings topic hub. Cluster counts from this site's insider trades database (cluster flag as recorded on each filing), computed November 5, 2026.