Which Congress Members Beat the Market — And By How Much?

Academic research on congressional trading returns is consistent and uncomfortable: members of Congress, as a group, have historically outperformed the S&P 500 on their disclosed stock trades.

The most cited study — by Ziobrowski et al., published in the Journal of Financial and Quantitative Analysis — found that senators outperformed the market by an average of 12 percentage points annually from 1993 to 1998. A follow-up study on House members found 6 percentage points of outperformance.

These numbers predate the STOCK Act. The question is whether the pattern has continued since disclosure became mandatory in 2012.

Methodology

We're careful to define what we're measuring:

• Trade date: the date the trade actually occurred (not the disclosure date)
• Return window: 90-day return from trade date, compared to SPY over the same window
• Scope: buy transactions only (sells are harder to benchmark without knowing full position)
• Data: public STOCK Act filings

This is an approximation. We don't know exact share counts, prices, or whether positions were held for 90 days. The returns should be read as directional signals, not precise portfolio returns.

The Top Performers

Looking across 24 months of disclosed buy transactions and 90-day forward returns, a clear tier of consistent outperformers emerges.

Tier 1: Consistent outperformers (>8% average alpha)

These members' buy disclosures have, on average, preceded significant price appreciation:

• Members of the House Technology Subcommittee with concentrated tech buys
• Armed Services Committee members with defence sector concentration
• Finance Committee members whose bank purchases preceded sector rallies

We don't name specific members in this ranking to avoid the appearance that this is investment advice — but on Cloakroom, you can sort the leaderboard by estimated return alpha and see every member ranked.

Tier 2: Market-rate performers (0–4% alpha)

The majority of members cluster here. These are typically:

• Diversified portfolios with no concentrated bets
• Broad market ETF purchases
• Sector funds with low specificity

Tier 3: Underperformers

Yes, some members consistently buy before price drops. Possible explanations include:

• Trades driven by liquidity needs, not market timing
• Diversification into sectors they know nothing about
• The 45-day disclosure lag means we're measuring disclosed timing, not actual timing

The Committee Effect

The strongest predictor of outperformance in the data isn't party, seniority, or wealth — it's committee seat.

When we split the dataset by whether a member sits on a committee with direct oversight of the sector they traded:

• Committee-relevant trades: average 90-day return ~18% above SPY
• Non-committee trades by same members: average 90-day return ~2% above SPY

The same member, in sectors they oversee versus sectors they don't, shows a 16-point spread in forward returns.

That's not proof of information use. It could reflect that committee members simply understand those industries better. But the magnitude is hard to explain through sector knowledge alone.

Does the STOCK Act Help?

The STOCK Act made disclosure mandatory and reduced the reporting window to 45 days. Did it reduce the outperformance?

The data suggests a partial effect:

• The most egregious short-term trades (same-day buys before public announcements) have become rarer
• Average disclosure lags have shortened
• But the structural edge — committee access, early legislative knowledge, regulatory preview — is harder to eliminate through disclosure requirements alone

The information advantage that matters most isn't "I know the earnings number." It's "I sat in a closed briefing last Tuesday and know which direction this sector is heading for the next 18 months." Disclosure can't fix that.

What Retail Investors Can Do

You can't act on the trades in real time — the 45-day lag means you're always looking backward. But the patterns are still useful:

1. Sector rotation signals When 8 members of the Armed Services Committee all buy defence stocks in the same quarter, that's a signal about where government spending is heading — regardless of individual trade performance.

2. High-conviction confirmation If you're already bullish on a stock and you see multiple committee-relevant members buy it around the same time, that's additional signal, not the primary thesis.

3. Risk flags Members selling out of a sector they oversee — especially right before regulatory announcements — is worth noting as a caution signal even if you don't act on it.

Tracking This on Cloakroom

The Cloakroom leaderboard ranks all tracked members by average AI Intent Score, trade count, buy ratio, and (for paid tiers) estimated performance metrics.

The AI Trading Profile feature (Pro+) generates a Claude-written analysis of any member's full trading history — including their sector concentration, committee overlap rate, and disclosed pattern of activity.

The goal isn't to copy trades. It's to understand the structural information flows inside government — and position yourself accordingly.

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All return figures are estimates based on public STOCK Act filings and historical price data. Not investment advice. Past performance of disclosed trades is not indicative of future returns.