Methodology
Data. The universe is the S&P 500. For each company, Alpha Vantage's CONGRESS_TRADES endpoint returns its full history of trades disclosed by sitting members of Congress and their families under the STOCK Act. This page keeps BUY/SELL transactions from the trailing 24 months. A 90-day window, like Insider Buying/Selling's Form 4 window, would leave most S&P 500 names with no trades, since congressional activity in any one stock is sparse. Options, warrants and bonds reported under the same ticker are excluded.
The STOCK Act discloses trade size as a range (e.g. $1,001–$15,000), not an exact amount. Every $ figure on this page is the midpoint of that range, the same convention as Capitol Trades and Unusual Whales. Treat every dollar total as an estimate.
Disclosure lag. The chart measures days between the trade date and the date the Periodic Transaction Report was filed. The STOCK Act requires filing within 45 days of becoming aware of the transaction. Rows with a missing or implausible filed date (filed before the trade, or no date at all) are excluded.
Regression. It uses Pearson and Spearman (as on Factor Analysis) and takes each stock's 3-month return relative to SPY from Relative Strength Leaders/Laggards. Trades are disclosed well after the fact (up to 45 days, often longer per the lag chart above). Any relationship here is about revealed skill or information, not a signal an outside investor could have traded on before the disclosure.