Last week I tested insider buying. You asked about Congress, so I analyzed 17,859 disclosures

Last week I shared my study of 47,458 corporate-insider purchases. One of the main questions in the comments was whether members of Congress perform better, so I ran the numbers.

I analyzed 17,859 congressional purchase and sale events disclosed between January 2020 and August 2025, entering only after each disclosure became public.

Short answer: copying Congress did not beat the S&P 500.

The typical congressional purchase returned 10.95% after one year, while the S&P 500 returned 19.73% over the same windows. Sales performed similarly, and purchases did not reliably beat sales.

Congressional purchases did underperform by less than the corporate-insider purchases in my previous study. I also found some evidence that purchases were better timed than later placebo windows on the same stocks, but they still trailed the market.

I tested disclosure delays, transaction-date returns, committee-aligned purchases and two placebo windows in the full study.