Do politicians beat the market?
The research does not agree. Two studies of trades from the 1980s and 1990s found that members of Congress beat the market. Later studies of 2004 to 2008 and of 2012 to 2020 found that, on average, they did not. A 2025 working paper found higher returns for members after they moved into leadership positions.
The studies
| Study | Who and when | Finding |
|---|---|---|
| Ziobrowski, Cheng, Boyd and Ziobrowski (2004) | Senators, 1993 to 1998 | A portfolio copying senators' purchases beat the market by 0.85% a month. A portfolio copying their sales lagged it by 0.12% a month. |
| Ziobrowski, Boyd, Cheng and Ziobrowski (2011) | About 300 representatives, 16,000 trades, 1985 to 2001 | A portfolio copying their purchases beat the market by 0.55% a month, about 6% a year. |
| Eggers and Hainmueller (2013) | Trades and holdings of members, 2004 to 2008, and a new look at 1985 to 2001 | No sign that members traded with an information advantage in either period. From 2004 to 2008 the average member would have earned more in a passive index fund. |
| Belmont, Sacerdote, Sehgal and Van Hoek (2022) | Senators and representatives, January 2012 to December 2020 | No evidence of better returns. Shares House members bought did 0.26% worse over six months than the benchmark. |
| Wei and Zhou (2025) | Members who moved into leadership positions, compared with similar members | Before becoming leaders their returns matched the others. Afterwards they did better by 47 percentage points a year. This is a working paper from November 2025. |
Why the results differ
- Different years. The first two studies cover the 1980s and 1990s. Eggers and Hainmueller cover 2004 to 2008, and Belmont and his co-authors the years after the STOCK Act of 2012, when trades had to be reported within 45 days.
- Different methods. A portfolio that copies each trade weights the members who trade often. A study of holdings counts every member who owns shares, including those who seldom trade. Eggers and Hainmueller used both, and their reading of the 1985 to 2001 data challenges the timing the two earlier studies found.
- Averages hide single trades. Belmont and his co-authors write that their method cannot rule out informed trades hidden in an average, or trades before 2012.
- One group, not all members. Wei and Zhou look at members who moved into leadership positions, a small group within Congress.
Why this site does not rank members by return
A report gives each trade as a range, such as $1,001 to $15,000, and a member can file up to 45 days after the trade. A return per member built from those reports rests on estimates, and a ranking on it would read as a judgement of a person. This site counts reported trades instead, in which members of Congress trade the most?.
Congress trades on this site
Politician Search lists each member's reported trades with a link to the original report. The rules behind those reports are in can members of Congress trade stocks?, and research on trades by company insiders is in do insider purchases predict stock returns?.
Checked against the regulation and the regulator’s own pages on Oct 31, 2026. This guide explains the rules; it is not legal or investment advice.
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