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About

Open methodology. Public data. Rigorous filtering.

ClusterSignal is powered by SEC EDGAR Form 4 filings and enriched with StockFit sector data and Yahoo Finance market context. We document exactly how clusters are detected, scored, and filtered — so you can evaluate the signal quality yourself.

Why clusters, not just trades

Insiders sell for a hundred reasons that have nothing to do with the stock — paying for a house, taxes, diversifying. A single sale tells you almost nothing.

Buys are different. Insiders only buy because they think the price is going up. And when three or more execs at the same company write personal checks for shares within the same short window, that's not noise — that's a coordinated bet from the people who actually know what's happening inside the business.

ClusterSignal filters for that pattern specifically, instead of dumping every Form 4 filing into a table and leaving you to find the signal yourself.

Data sources

All insider transaction data is extracted from public SEC EDGAR Form 4 filings. These mandatory disclosures cover open-market purchases, sales, option exercises, and other transactions by company insiders (executives, directors, and 10%+ holders).

Sector and industry classification is sourced from StockFit. Price context — current price, 52-week range, market cap, P/E ratio, earnings dates, and news headlines — is fetched from Yahoo Finance and cached per ticker. We do not use any non-public, proprietary, or insider-only sources.

Detection methodology

A cluster is flagged when 3 or more distinct insiders file Form 4 open-market transactions (purchases or sales) for the same company within a rolling 5-day window.

Transaction floors eliminate noise before cluster detection runs. Trades under $5,000 total value are ignored for all insiders. VP and Director-level trades under $10,000 are excluded. CEO and CFO trades under $25,000 are excluded. The aggregate cluster value must exceed $50,000 before a cluster is created.

The poller scans SEC EDGAR every 30 minutes using the EFTS feed. New Form 4 filings are parsed for non-derivative transactions, stored, and immediately evaluated for cluster patterns. Existing clusters are not duplicated — each unique combination of ticker, direction, and overlapping window is stored once.

Scoring methodology

Each cluster receives a weighted composite score from six independently weighted factors:

  • Insider Count (up to 60 pts): 15 pts per distinct insider. The single highest-weight factor — coordination matters more than any individual trade.
  • Seniority (up to 30 pts): CEO scores 30, CFO 27, President 23, VP 10, Director 7. C-suite insiders carry roughly 3× the weight of VPs or Directors, reflecting their broader information advantage.
  • Capital Deployed (up to 22 pts): Scale-adjusted. $2M+ cluster earns 22 pts. $50K earns 2 pts. Larger real-money commitment correlates with higher conviction.
  • Time Velocity (up to 15 pts): Trades in a single day score 13–15 pts. Trades spread over 3+ weeks score 0. Tight compression is rare and statistically meaningful.
  • Filing Speed (up to 12 pts): Insiders who file the same day as their trade earn maximum points. Voluntary prompt disclosure suggests the insider chose visibility.
  • Win Rate (up to 22 pts): Historical 90-day returns from prior clusters by the same insiders on the same ticker. Only computed when enough prior data exists.

Grade thresholds: A (≥82), B (≥52), C (<52).

Short Radar

SOLD clusters and SHORT RADAR clusters are distinct. Short Radar is reserved for sell clusters that pass additional filters: $500,000+ aggregate value with 3+ distinct sellers — or $250,000+ if C-suite insiders (CEO, CFO, President) are among the sellers. These filters are designed to separate large coordinated liquidations from routine diversification or tax-driven sales.

ClusterSignal also parses Form 4 footnotes to detect 10b5-1 plan language. Routine pre-scheduled plan sales are noted as such. Amended or modified 10b5-1 plans are treated as higher-conviction, since the insider voluntarily changed a pre-committed program.

What the scores are not

Scores are research inputs, not investment recommendations. A Grade A cluster does not mean a stock will go up. A Short Radar flag does not mean you should sell or short. Insider activity is one signal among many. Evaluate each cluster alongside earnings context, valuation, sector trends, and your own research.

Past cluster patterns do not guarantee future results. ClusterSignal is not a registered investment advisor. Nothing on this site is financial advice.